**LIFE** -
I. PHILOSOPHY
I. Notions. In contemporary philosophical language, "v." denotes, in the strict sense, "a set of phenomena (particularly: nutrition and reproduction) proper to beings endowed with a certain degree of organization." By analogy, the term is applied to certain super-individual structures which, within the human plane of the "objective spirit" (objektive Geist) in the Hegelian sense or in the less systematic sense of the Geisteswissenschaften, manifest an activity of self-organization, of irreversible transformation: growth and death; thus the "life" of artistic forms, of civilizations, of societies, of language. From a phenomenological point of view, three degrees of determination of the living are distinguished: a) the empirical-pragmatic of common sense; b) the empirical-scientific of the biological sciences; c) the properly philosophical degree (v. IMO10GIA and infra II).Despite the difficulty of rediscovering, beneath the cultural evolution of concepts, the original aspect and despite the confusion of empirical concepts, the convergent data of ethnological investigation and of child psychology lead to the affirmation that man has the original tendency to consider all bodies as living and endowed with intentions (cf. Piaget, *La représentation du monde chez l'enfant*, Paris 1926, p. 160). Thus animism and anthropomorphism would determine the two components of the primitive empirical concept of "v.": spontaneity of movements and their intentional expression; as well as the "place" where we perceive them, the human world, which for some would be the first to be grasped (cf. L.-A. Feuerbach, *Grundsätze der Philosophie der Zukunft*, Leipzig 1846, §32, p. 231). This assertion is taken up by some existentialist philosophers (e.g., M. Buber, who in *Ich und Du*, Fr. tr., Paris 1938, p. 50, distinguishes between a general "animation" of the world and the instinct of cosmic relation which makes things into a "thou" opposed to a "that" of interested and scientific investigation). Hence: human world, animal world, plant world, inorganic world, in the opposite sense of the ascending ontological hierarchy which does not necessarily coincide with the phenomenological order (cf. H. Bergson, *Essai sur les données immédiates de la conscience* [Paris 1936, p. 108], for whom the idea of inertia, as negation of spontaneity, is genetically simpler than the latter).
The origin of this perception of "v." (a question intimately connected with that of the perception of the other's psyche) has been explained both by an "empathy" (Einfühlung) which projects our own "life" into things (on the theory of Einfühlung, cf. Th. Lipps, *Ästhetik*, p. 355, in *Die Kultur der Gegenwart*, VI, part 1, Berlin 1907); and by an induction which, from the analogy of expressive movements, concludes with a similarity of animation; and as Scheler explains it, admitting it both for the apperception of "vital centers" (Vitalzentren) and for that of "spiritual centers" (Geistzentren; cf. *Wesen und Formen der Sympathie*, 5th ed., Frankfurt a.M. 1948, pp. 252-87, esp. pp. 255-56), through an a priori of an almost emotional order (irreducible to an innate idea and to a proper intuition) which immediately reveals in an organic and expressive tonality the vital sense of these movements. In conclusion, an "immediate" apperception of the living seems more probable, grasped as a "concrete meaningful totality" (St. Thomas attributes this to the "cognitive": cf. *in De Anima* [ed. A. M. Pirotta, Turin 1925, n. 396]), where the central phenomenon is the *movere seipsum*, according to the various functions of "v." The specific concept of vegetative life is relatively late. Some ethnologists believe that attention to the life of plants developed particularly in matriarchal civilizations (v.).
2. History
a) Ancient philosophy. - In ancient philosophy three main orientations are distinguished: a cosmic conception of "v.", an anthropological conception, and a more expressly biological representation. The first, represented above all by Heraclitus (and taken up by Stoicism), presents a "cyclic" becoming (ἐπὶ κύκλου: H. Diels, *Vorsokratiker*, 6th ed., Leipzig 1910; B. 103) animated by a "fire always alive" (πῶς ἀεὶ ζῷον: ibid., 30), whose terms are susceptible to reversible transformations according to a law of unity and return.For Stoicism, the entire world and its evolution form a living being; "the becoming of being is analogous to the evolution of the living" (cf. E. Bréhier, *La théorie des incorporels dans l'ancien stoicisme*, 2nd ed., Paris 1928). Being is assimilated to a "seed," which, developing by virtue of an immanent causality, configures it into a defined structure (on Stoic terminology relating to life cf. G. Kittel, *Zähe*, in *Theol. Wörterb.*, II, pp. 838-39; on classical usage, pp. 833-38). The anthropological conception is affirmed with Plato, for whom the world is also a "perfect animal" (*Tim.* 23 d), similar to its intelligible paradigm (ὁμοιον τῷ παντελεῖ: ζῷον, *ibid.*, 31 b). But here the "logos" is more manifestly assimilated to a "law" (νόμος) which informs it (*Phil.* 30 d). And the world of the immutable Ideas seems to animate itself with a kind of internal δύναμις which could suggest a complete assimilation of the Ideas in living thought. Being is οὐκ ἄλλο τι πλὴν δύναμις (*Sophist*, 247). In contrast, A. Diès asserts (*La définition de l'être et de la nature des Idées: le Sophiste de Platon*, Paris 1932, ch. 2) that there is already a clear tendency to define "v." through intelligence and not merely on the human plane. But it is above all in Plotinus that every form of life is ἐνέργεια (*Enn.*, III, 11, 16-18, ed. E. Bréhier, Paris 1927); this "energy," however, is itself an obscure concept: πᾶσα ζωή νόησις τῆς (*Enn.* III, VIII, 8-17). The degrees of life are thus the same as the degrees of thought, of a thought ever clearer. Contemplation is life par excellence (*Enn.* III, VIII, 8.26-30); and, in truth, all beings are "contemplations": θεωρία τὰ πάντα ὄντα (*ibid.* 26). But the Good from which life springs is not living (*Enn.* VI, VII, 15).
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**LIFE** - The Tree of Life, according to the Buddhist legend contained in IOSAPHAT (v.). Reliefs by B. Antelami in the lunette of the southern portal (c. 1200) - Parma, Baptistery.
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c) Renaissance philosophy returns to the Stoic conception which considers the world as a great animal; vital energy, according to a naturalistic mysticism (represented by the names of Paracelsus and Bruno [v.]), unfolds in all the manifestations of the cosmos.
d) Modern philosophy reacts against this pantheism with mechanism, which finds systematic expression in Descartes: he substitutes the mind for the soul of the ancients (Oeuvres, ed. A. Tannery, VII, Paris 1905, p. 356) and presents the paradoxical theory of animals-machines, applied even to the human body (ibid., XI, 223 ff.; Traité de l'homme, ibid., p. 120 ff.; Traité des Passions, ibid., pp. 330-331). This theory was taken up by Malebranche (Recherche de la vérité, V, ch. 3, cf. also H. Bousson, La religion des classiques, Paris 1948, ch. 7) and found its radical expression in the theory of man as a machine, which was embraced by physicians and materialist philosophers of the 18th century (La Mettrie). Leibniz attempts a compromise between Aristotle and Descartes. The world, without having a soul (cf. Leibniz, Textes inédits, ed. J. Grua, Paris 1910, p. 558), is filled, in its smallest parts, with vital principles or entelechies (Considérations sur le principe vital, in Opere varie, tr. it., Bari 1912, pp. 75-83), immortal because indivisible, endowed with confused perception and appetition, without influence on the world of bodies: thus a new dualism arises in the tension between the realm of final causes (world of v.) and efficient causes (world of bodies and mechanism), which pre-established harmony makes externally accordant. This psychic spontaneity, whose freedom is a particular case (cf. Textes inédits, ed. J. Grua, p. 287 ff.), is closely linked to the thesis on substance-force, on the 'conatus' (cf. L. Jabbert, La théorie leibnizienne de la substance, Paris 1947, ch. 1-3). For Kant, the immanent finality of the living being, in opposition to aesthetic and hedonistic finality, is objective, i.e., referred to things (Kritik der Urteilskraft, Lp. 1948, p. 161); it is material or real and not merely formal, as in the case of geometric figures (§ 62); it is intrinsic, in opposition to extrinsic finality, where a means serves man: since organized beings are for themselves 'ends of nature' (Naturzwecke, § 65), cause and effect of themselves (sich bildende Kraft) causa sui.
e) Modern philosophy. Hegel tends to reconcile the two aspects of finalism and mechanism as the two aspects of necessity and freedom (cf. Logik, ed. G. Lasson, II, Leipzig 1945, p. 387). In the Hegelian conception, V. presents three aspects: a) theological-religious (in the Theologische Jugendschriften): V. implies interiority in opposition to the aesthetic exteriority of the law and to the master-servant dualism, which characterize the Old Testament (ibid., pp. 4-16); interiority that expresses the law of love and the relation of the Father to the Son, proper to Christianity, through freedom. b) Logical-dialectical: V. is the immediate form under which the Idea appears (Logik, ed. cit., vol. II, p. 412), as dynamic subjectivity: end and cause of itself. V. presents three moments: the living individual as constituting subjectivity and self-determining organizer of its matter; the constituted individual whose properties are sensibility, irritability, reproduction, vital processes that unfold a relation in the external environment which the living being destroys by assimilating it, need and impulse (Bedeutungslehre, p. 27). c) Kant: which are completed in appropriation, genus (Gattung) that inserts the individual into a chronological series and makes it a member of a species to which it participates (ibid., 426 ff. and Encykl., § 369-70). d) Hegel: logical: V. as interiorization of its object and reflection upon itself and constitutes the first stage toward Selbstbewusstsein under the form of desire for itself, negative because destroyed by its object (Phänomenologie des Geistes, ed. W. Hoffmeister, Leipzig 1948, p. 135 ff.). The romantic conception of V. has as its principal representatives Schelling, Schopenhauer, and Nietzsche, who does not conceive the living being as the foundation of itself, causa sui, on account of the necessary relation of the parts in the whole and of the whole in the parts, and thus presents itself as an immanent concept (inwohnender Begriff) in which matter and form are inseparable (Ideen zu einer Philosophie der Natur, in Schellings Werke, I, Leipzig 1907, p. 134 ff.).
unity of nature and of freedom, of necessity and of contingency, of mechanism and of finalism. The soul, principle of life, cannot be either a force nor a juxtaposition of forces since it must harmonize these forces, but rather a spirit (Geist als Prinzip des Lebens gedacht heisst Seele, ibid., p. 147). This principle, common to all living individuals, is not proper to any one of them, just as the same spirit is infinite and absolute and limits itself, through the force of a negative principle of individuation, within the variety of species and individuals (Von der Weltseele, ibid., p. 599). Consequently, it is called: «Gemeinschaftliche Seele der Natur» (ibid., p. 665), and the whole of it, taken together, is an 'allgemeiner Organismus', a whole in which bodies are beforehand «dead life» (erloschenes Leben). The essence of all things is therefore life (ibid., p. 596). And life itself is nothing but the manifestation of this creative genius, immanent (Ideen, p. 322) to its work in the universe, which we can recognize through an «intuition» (Anschauung).
Schopenhauer rejects the World-Soul because it implies a consciousness and a knowledge that do not suit all beings (Die Welt als Wille und Vorstellung, in Schopenhauers sämtliche Werke, ed. J. Frauenstädt, III, Leipzig 1873, p. 398). Life is at once the immediate and fundamental object of the will of the noumenon (Wille zum Leben, Drang und Trieb zum Dasein) and the core of reality: from here the world and one of the objectifications of this will of the noumenon originate, whose first degree is the inorganic world (ibid., II, 1873, chaps. 17-29). The living being differs from the whole in that the latter exhausts in one stroke the law it expresses (thus the stone that falls adequately explains gravity; ibid., II, chap. 28, p. 185); instead, the plant or the animal is insufficient to the specific idea it tends to explain, and while the former is subject to the equality of action and reaction that governs causality, the living being manifests a reaction absolutely disproportionate to the «stimuli» that provoke it (ibid., II, chap. 23, pp. 137-38; regarding the distinction between Ursache, Reiz, and Motivation cf. also Über die Freiheit des Willens, Sämtl. Werke, cit., IV, 1874, p. 29 ff.). Hence, in the living being, a plasticity, an individuality, a spontaneity (Über den Willen in der Natur: Sämtl. Werke, IV, pp. 60-64) that lends itself with greater difficulty to the rigidity of mechanical and mathematical laws, though necessity is nonetheless present.
Eduard von Hartmann unites Schopenhauer’s unconscious will with the unconscious idea into a single principle called the Unconscious (Philosophie des Unbewussten, tr. franc., I, Paris 1877, p. 5), an idea without which this will would be empty and without object (ibid., p. 33). This unconscious manifests itself in the life of the body as in the human spirit: but it is especially clear in the organism under the form of organic finalism.
Nietzsche, in his essay on the «transvaluation of all values,» gives to life a value-laden sense of supreme worth. Far from negating it, as in Schopenhauer, life must, under the form of the «will to power» (Wille zur Macht), affirm itself against all degenerative tendencies that he attributes to civilization and to Christianity. This will to power already asserts itself in the inorganic world in the form of a conflict of forces (Wille zur Macht, I, Paris 1909, pp. 206-98); more distinctly in the organic world as the struggle of individuals and species; in the human world in the form of science (ibid., pp. 274-275) and of power, and in a more veiled aspect in morality itself (ibid., pp. 339-50). Life and will to power are synonyms of intense energy. Idealized as supreme value, the will to power—which is life—finds in Zarathustra the symbol of the «perfect living being,» the «Übermensch» (cf. Also sprach Zarathustra, book III, Paris 1946, p. 227 ff.).
In positivism, A. Comte seeks to free biological phenomena from theological interpretations (by means of arbitrary will) and metaphysical ones (by means of an individual or cosmic psyche) in order to subject them to the positive exigency of explanation by laws. Thus explained, the biological phenomenon is summarized in the correlation of two elements (Discours de philos. posit., III, Paris 1908, p. 141 ff.).
H. Spencer, concerned with problems of genesis and dominated by the idea of evolution, starts from the concept of «force» (as an unconscious substratum of all cosmic phenomena). Plants and animals are transformations of force through integration of matter and concomitant dispersion of movement. Evolution is nothing other than «the change from an incoherent homogeneity to a coherent heterogeneity as a result of such integration and dispersion.» Dissolution follows the inverse path (cf. First Principles, tr. franc., J. Cazelles, Paris 1871, ch. 6).
According to Bergson, the essence of life is the «creative duration» that can be grasped through intuition; life presents itself as a «whole» irreducible both to extrinsic finalism and to intrinsic finalism limited to a single organism (since in nature there is no absolutely clear individualism). But if the whole is original and does not reduce to an integration of parts, as Spencer believed, what leads us from mechanism to constructive finalism is an original vital impulse (élan vital), a simple movement whose evolution does not unfold in successive degrees of a single tendency (vegetative life, instinctive, rational), but in three divergent directions. The plant, the animal, and man are the three divergent directions of an activity that has split in its development (L'Évolution créatrice, Paris 1946, pp. 1-7).
3. Critical discussion
One notes, particularly in contemporary philosophies, a shift of emphasis from the ontological to the axiological, inasmuch as life, understood as a principle, tends increasingly to be interpreted as a value. Hence the affective-axiological resonances of the term. Such divergences may cast doubt on the unity of the concept of life; however, when brought back to its original characteristic, life has suggested to philosophical speculation the following aspects: a) first, the immanence of agency (rather than the spontaneity valid for every natural action; cf. the observations of C. Fabro on the work of F. De Sarlo, Vita e Psiche, in Bollettino filosofico, 3 [1937], pp. 65-77), so well highlighted by St. Thomas; b) then, or consequently, causality, whose «schema» is the organism in the embryonic phase (on biological schemas in Aristotle, cf. H. Donovan-Hantz, The Biological Motivation in Aristotle, New York 1937); c) fruitfulness (wonderfully developed by St. Thomas in Contra Gent., IV, 11). This structure of the concept of life, when brought back to its intelligible degree, does not exclude in the least, but rather implies, the affective-axiological characters clarified by Romantic philosophies and contemporary Lebensphilosophien.II. ORIGIN OF LIFE
4. Characteristics of the Living
There is unanimous agreement in recognizing that there are differences between inanimate bodies and living beings. These, however, do not concern the material elements of the one and the other, since it is now established that organisms are composed of the same elementary substances that make up much of the inorganic world: carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus, chlorine, calcium, sodium, potassium, magnesium, with traces (often of great importance in function) of iron, iodine, zinc, copper, manganese, cobalt, rubidium, etc. Nor do the individual molecular aggregations that these atoms assume in the living, although far more complex than those found in inorganic nature, seem in themselves to mark a characteristic of the living, as was once believed, since such compounds can, at least theoretically, be produced in the laboratory, as has already happened in some cases. Thus, Wöhler (1828), by heating cyanic acid and ammonia, obtained urea identical to that which Rouelle had found fifty years earlier in mammalian urine; similarly, a few decades later, Kolbe synthesized acetic acid, Berthelot fats, and at the beginning of the century Fischer achieved the synthetic formation of polypeptides. Recently, Betti succeeded in synthesizing those optically active compounds that nature presents as such, but which our syntheses hitherto produced only as racemic mixtures, i.e., as a blend of dextro- and levorotatory compounds. Naturally, we are still far from having achieved, by artificial means, the complexity of organic molecules; but theoretically, nothing prevents us from doing so.The radical differences arise from the fact that even the most elementary organisms nourish themselves, grow, reproduce, are irritable, age, and die, whereas nothing of the kind is found in the inorganic world. The organism nourishes itself through intussusception, drawing to itself heterogeneous material particles, transforming them through a long process of molecular composition and recomposition, and impressing upon them its own specific structure. In this way it increases its volume, if it has not yet reached the adult stage, up to a limit characteristic of the various species; at the same time it differentiates its individual parts through cytological and anatomical formations of the most diverse structure, and establishes a constant material and energetic exchange with the surrounding world. Once adult, and sometimes even at juvenile stages, the unicellular as well as the multicellular organism is always capable of giving rise to other individuals of the same species, either by dividing itself into two or more nearly equal fragments or by entrusting this function to particular cells whose sole task is to transmit V.
It is sometimes objected that crystals exhibit some analogous manifestations. Like the living being, the crystal is born from the mother liquor, grows by attracting to itself other particles of the crystallizable substance in solution; in this growth, the particles do not assume the indifferent and chaotic arrangement of vitreous substances, but, just as cells derived from the fertilized ovum take up fixed positions in the embryo characteristic of each species, so in the crystal atoms and molecules are arranged with a remarkable order, giving rise to geometric figures characteristic of the various bodies. And other analogies. In reality, there is no real similarity between the two series of phenomena. The birth, if one wishes to call it such, of a calcite crystal, for example, occurs when, in a solution of calcium carbonate, some molecules first assume the rhombohedral spatial arrangement. No chemical reaction takes place: calcium carbonate was in the solution, calcium carbonate remains in the crystal; what is new is merely the form, as the spatial arrangement of the molecules. And from this moment onward, one already has a perfect calcite crystal, which increases in volume without limit by attracting along its edges and faces other elementary calcite crystals identical to it, not derived or transformed from it but formed in the mother liquor. And as it grows, instead of acquiring heterogeneity or a new form, it merely makes visible the submicroscopic form of the primitive lattice. Thus it is not an individual that grows and builds itself up, as in the living being, but new identical elements that, without losing their own nature or individuality and without acquiring anything from the union, are superimposed upon one another according to well-defined laws, thereby increasing the volume of the whole.
Every organism, after a certain period of existence characteristic of the various species, ages and dies, whereas nothing of the kind occurs even in crystals, which represent the highest manifestation of activity in inorganic matter. Nor do microscopic beings and the germ cells of higher organisms make an exception to this law, for even in these cases the original individual perishes in time, although part of its matter lives on in the offspring.
Another characteristic of the living is irritability, defined by Cl. Bernard as the property of the living element to act according to its nature under an external provocation (Leçons sur les phénomènes de la vie commune aux animaux et aux végétaux, Paris 1878, p. 248). It comprises all the phenomena by which living beings react to stimuli from external factors such as light, gravity, electricity, contact with a mechanical body, air, water, humidity, chemical substances, etc., and it differs from the activity of inorganic matter in that the reaction by which the living being responds to an external stimulus is, from time to time, elaborated by the living being itself; it is therefore variable from organism to organism and from one physiological moment to another. And if, in order for a stimulus to act, a minimum intensity is required, once a certain limit is exceeded the organism either no longer reacts or reacts in a direction opposite to the stimulus.
5. Origin of life
While there is universal agreement in recognizing that the aforementioned operations are characteristic of living beings, there are great divergences among scholars in interpreting them and, consequently, in the problem of the first origin of life.Some still consider plausible the hypothesis of cosmozoa or of interstellar panspermia, proposed by Richter (1865) and later shared by eminent scientists such as W. Thompson, Helmholtz, Van Tieghem, Bonnier, Arrhenius and others, who also attempted to resolve the serious physical and biological difficulties connected with II. Briefly, the hypothesis holds that life established itself on earth through germs coming from other already inhabited stars. It is superfluous to examine whether those difficulties are truly resolved by the explanations offered by various authors; the fact remains that the problem of the first origin of life is not solved but merely shifted from the earth to the star or stars from which it is supposed to derive.
Materialists affirm that life originated on our earth through spontaneous generation from inorganic matter, as it is improperly called. Already Emerson, Dewey, Dario, Aristotle and other Greek philosophers, Lucretius and Virgil among the Latins, and in a certain way even St. Thomas and ancient Scholasticism, upheld the same doctrine, and everyone knows that until the 1600s it was peacefully accepted, being thought that such autochthony continued to occur, at least for lower organisms. The materialists’ assertion thus seemed proven. Yet Fr. Redi (Esperienze intorno alla generazione degli insetti, Florence 1668) began to demonstrate that the worms developed from putrefying meat do not originate spontaneously but from eggs laid there by flies; A. Vallisneri (Storia della generazione dell’uomo e degli animali, Venice 1715), together with Malpighi, showed that larvae present in galls and in fruit also derive from insect eggs; Spallanzani (Osservazioni e sperimenti intorno agli animaletti delle infusioni, Modena 1765) extended the same demonstration to infusoria, discovered a century earlier by Leeuwenhoek; and finally Pasteur proved (1860), against Pouchet, that even microscopic bacteria do not derive from inorganic matter but from preexisting bacteria.
With these observations, the demonstrative proof of spontaneous generation thus vanished, and materialists, in support of their thesis, resorted and still resort to attempts to manufacture life in the laboratory, to filterable viruses (v.) and to other presumed organisms even simpler that, at the beginning of life, would have originated from inorganic matter. But attempts to manufacture life have always and only led to the construction of inanimate toys; the primordial existence of organisms simpler than viruses is a pure presumption unsupported by any factual data, devised solely to save the thesis; as for viruses, it is still debated whether they are living, whether they are authentic organisms or fragments of organisms, and there is no proof of their spontaneous origin, while their strictly obligate parasitism excludes in every way that they could have been the first living beings. In conclusion, the so-called spontaneous generation, foundation of the materialist hypothesis, has no experimental proof at all, and all the evidence we have is against II.
C. E. Guye (L’évolution physico-chimique, Paris 1922) and Lecomte du Noüy (L’homme devant la science, ibid. 1939) have also mathematically calculated the probability of the causal formation of a single protein molecule, much simpler than those actually found in living beings, reaching the conclusion that it is theoretically so improbable as to be practically impossible, just as it is practically impossible for a watch to form spontaneously, even though it is far less complex than a living being.
Among mechanists, for whom organisms are to be likened to machines constructed by nature, some are materialists and the observations made above and those to be made later apply to them; others are more or less openly theists and, while denying that in the living being there are principles different from the chemical-physical forces of their material constituents, admit, with Descartes, that it was God’s power that formed these most perfect machines by bringing about those chemical combinations and physical aggregations that the materialists’ chance cannot produce. All the difficulties raised by spontaneous generation disappear in this view. But while it escapes the difficulties regarding the origin of life, it fails to adequately explain the intrinsic unity proper to every organism, as manifested through its operations.
Vitalists also admit that, at the origin of life, there was a direct intervention by God, but not restricted merely to forming some highly improbable chemical combinations; rather, it extended to endowing the first or earliest organisms with principles different from and superior to the physico-chemical forces that alone operate in the inorganic world. A doctrine already upheld by ancient naturalists such as Aristotle, revived by Scholasticism and resurrected in modern times, especially through the work of Driesch; a doctrine that, both in the origin of life and in the operations of living beings, does not deny the importance of matter; it denies that matter alone is sufficient to produce life or to explain its characteristic activities.
There is great reluctance among scientists to accept that in living beings there are principles and forces different from the physico-chemical ones that can be measured with appropriate instruments; yet if one wishes to grasp the fundamental element that characterizes life, one is forced to do so in the name of that logic from which even the experimental scientist cannot dispense.
6. Essence of life
Whoever, in fact, considers with absolute objectivity the development and mode of operation of any organism must admit a coordination, subordination and convergence of its most varied activities toward the good of the whole. Every organism, despite the countless number of cells that perhaps compose it, presents itself as a natural unity in which the individual parts, whether macro- or microscopic, lose their autonomy, merging into the great harmony of the whole. To clarify these concepts better, it is appropriate to note some facts in a multicellular organism, where the phenomena unfold with greater evidence.In fertilization, which marks the beginning of a new life, this new natural unity is constituted. While in the divisional process of a cell the chromosomes split longitudinally, migrate in double rows to opposite poles of the nucleus, and the membrane, constricting, divides the cytoplasm and nucleus into two halves
Only in equal cells; in fertilization, by contrast, the paternal and maternal germ cells inseparably mix their cytoplasms, the respective chromosomes pair off two by two, having—almost in anticipation of this fusion—halved their number, and are enclosed within a single cellular and nuclear membrane, immediately giving the impression that two elements derived from different organisms constitute a single cell. Indeed, this cell already contains, potentially, the entire future organism and that specific organism. To realize this, it must multiply itself countless times and gradually differentiate the parts that will form; yet nothing normally occurs that is not already, in some way, contained within it, nothing that does not bear its influence. It will draw from the external environment the nourishment and oxygen needed to grow and produce the necessary chemical reactions, but above all, it will demand that the environment neither hinder its path nor slow its evolutionary momentum. This momentum is inherited by the first blastomeres derived from the fertilized ovum. They too enlarge, and once they reach a certain size, they divide in turn, always transmitting to their daughter cells the same drive to realize the complete future organism.
Morula, blastula, gastrula—these are successive stages of this unceasing journey in which the cells, ever more numerous, continue to cooperate toward the achievement of the single end. And just as each cell had a precise function before, now every group has a well-defined task to perform; if one group becomes incapable, its role is assumed by cells from another sector, so great is the shared urgency to fulfill the mission entrusted to them—almost *in solidum*—by nature.
Every cell nourishes itself, and the intake of materials occurs through the membrane. Now, the permeability of the membrane is certainly conditioned at every instant by its physical state and the chemical equilibria on its surfaces. But it is known that these conditions vary incessantly, and not by chance, so that the membrane’s permeability continuously changes qualitatively and quantitatively, now allowing the entry of substances it previously excluded, and in the measure required—not only for itself but for the entire cell. Indeed, this intrinsic selective power extends beyond the cell’s needs, aiming also at the needs of neighboring and distant cells, and even at the future needs of the developing organism.
The living being thus comes into being gradually, through an internal self-construction and a control that extends in space and time over an ever-growing matter, which assumes living properties and cooperates in producing those organ-forming substances that do not create life but are produced and used by life as means for new constructions. In this intense work—of which every biologist is aware—one can observe, along with the materials employed and the succession of different structures, the absence of any element that coordinates and directs such numerous and disparate phenomena, now enhancing, now depressing the activity of individual parts so that the whole may be progressively and harmoniously constructed. And yet this directive cause must exist, since its effect does exist, and it must be intrinsic to the organism itself, unless one resorts to an unnecessary occasionalism with all its attendant difficulties.
This unity, in its various aspects of coordination, subordination of parts, and convergence of activities for the good of the whole, is still found in the adult, despite the fact that its cells do not form a true material continuity. To mention but a few facts: the various reactions composing a given metabolic cycle do not, as a rule, occur in the same location but begin in one organ and are completed by others, to which the intermediate products—still unusable by the organism—are carried by the blood. Alterations that may affect only a very limited region are felt throughout the whole, and it is the entire organism that intervenes, through the activity of many of its parts, to restore equilibrium.
There is moreover a phenomenon that, while confirming the unity of the living being, also opens a window onto the intimate nature of this property, revealing it as something irreducible to matter alone: the individual remains identical to itself, as the same organism, despite the incessant modifications in the physico-chemical state of its parts and the continuous material replacement of their components. All the matter present at any given moment transforms and is replaced by other matter; yet the individuality of the organism remains constant until its death, and man is fully conscious of this fact.
Finally, the unity of a living organism becomes even clearer, by contrast, in the coordination and subordination of its parts when one considers the phenomena occurring in *in vitro* cultures, where a fragment of tissue removed from the organism can be kept alive. These cells, once so closely coordinated in their operations, so sensitive to alterations affecting one of them, now become entirely independent and transform into as many individuals, in which no aspiration toward a single end or mutual collaboration is found. If one is pricked with a needle, only that cell reacts, while its neighbors remain utterly indifferent. Having lost the purpose of their function and differentiation, they lose both, often transforming into structurally indifferent cells. And, as if to make their newly acquired independence from the whole more evident, they also move apart spatially, each migrating on its own toward the edges of the slide, where, without further restraint or precise aim, they resume proliferating autonomously—exactly as a unicellular individual would.
Such is the biological reality that confronts anyone who studies life. The researcher finds before them beings composed of one or billions of cells, each in turn made up of an astronomical number of atoms and molecules also found in the inorganic world, yet here operating as parts of a whole that, through them, orderly and teleologically self-constructs, and as an adult, orderly and teleologically performs its various functions. Hence the need for a real principle, distinct from the physico-chemical forces of the individual inorganic bodies composing the organism, and superior in order to it, since it is capable of regulating activity, unifying action, and making the organism a whole from which multiple functions derive and for whose well-being they operate. It is to this very element that St. Thomas’s definition refers when he states that life is the intrinsic principle of immanent action.
It is the task of philosophy, not science, to investigate the nature of this principle and how it unites with matter; yet it is the biologist’s duty to acknowledge its existence, for it is an integral and principal part of that biological reality (living organisms) which forms the proper object of their studies.