SPIRITO. — It corresponds to the Greek πνεῦμα and νοῦς, and to the Latin spiritus and mens. Etymologically it means “breath,” “breathing” (the expressions “vital s.” and “animal s.” used by Bacon and Descartes [v.] refer to this) and thus presents a anima (v.). Used as a synonym for anima, it means the vital principle in general; but it is often identified with the rational soul (e.g., in Scholasticism, in Descartes, and in Leibnitz [*Monad.*, 82-83]) thought (v.), in which case it is opposed to the sensible. In a derived sense, one speaks of the s. of a doctrine, a book, etc., to indicate the central idea or animating principle, which is often opposed to the “letter.”
In Plato and Aristotle, the s. begins to acquire the meaning of an immaterial, unextended, incorruptible, immortal essence, although uncertainties and obscurities remain even in Aristotle himself, for whom πνεῦμα is still conceived materialistically (something intermediate between the body, σῶμα, and the soul, ψυχή). For the Stoics, πνεῦμα is subtle matter; in man it is a spark of the divine πνεῦμα or creative reason (λόγος στεματτινός: Stobo, Ed., I, 374), which is the active principle, the living universe; yet Seneca (Epist., 65, 22) opposes s. to flesh, and Marcus Aurelius identifies pneuma, or spiritual breath, with the incorporeal soul (Ric., II, 2). Neopythagoreans and Neoplatonists clearly distinguish (and this helps to define the concept of s.) among body, soul (ψυχή), and s. (νοῦς), Plotinus (v.) defines as the unity possessing multiplicity within itself (Enn., V, 9, 6). Thus s. comes to designate the creative principle.
Apart from the theological meaning it has in the New Testament (especially in s. Paul), Christian philosophy inherits—and enriches the meaning of—the concept of πνεῦμα as an immaterial vivifying soul distinct from ψυχή (Irenaeus, Hef., V, 12, 2). Origen (v.), who likewise distinguishes between ψυχή and πνεῦμα, makes the latter the principle of judgment concerning good and evil, truth and falsehood (De princ., III, 1-5); and St. Augustine (v.), who distinguishes between ratio and intelligentia (inherent in mens), identifies spiritus with the faculty of forming, combining, and dissociating similitudines corporales (De Gen. ad litt., XIX, cap. 23, n. 49), the fruit of the soul’s activity. When, however, he uses it in the biblical sense (De anima et eius origine, II, cap. 2, n. 2), he does not distinguish it from mens. Christian philosophy is responsible for the clarification and deepening of the distinction between s. and body, and for the new and more complex meaning of the concept of s. (v. SPIRITUALISATO).
In modern philosophy, on the one hand, Descartes makes spiritual substance (res cogitans) the opposite of res extensa (Principia, I), while Spinoza makes it one of the attributes of divine Substance, constitutive of its essence, insofar as God is res cogitans and res extensa (Eth., part 2ª, De mente, propositions I-II); on the other hand, empiricism (v.) identifies s. with the totality of representations and consequently denies that it is a substance (Hume, Treatise of human nature, part 4ª, sections 5ª and 6ª). On the basis of the Kantian concept (v. KANT) of the transcendental, whose a priori forms are modes of functioning, transcendental idealism gives the concept of s. a gnoseological-metaphysical scope, opposing it to matter (the antithesis between the unity of thought and empirical multiplicity) and to nature (the antithesis between the creative I and created things, between the I that is freedom and necessity). S., understood as Egoity (Fichte) or as absolute thought (Hegel), an impersonal active principle, is the creator of total reality. Immortality belongs solely to it, and not to empirical selves. GENTILI (v.), Hegel’s Pure Thought becomes Thought in act, the dialectic of thinker and thought. Thus the concept of spiritual substance is destroyed, and s. is brought into conformity with nature. The term esprit retains a meaning of its own in Pascal (v.), signifying either a multiplicity of perspectives of knowledge (gnoseological pluralism) or special aptitudes: esprit de géométrie, esprit de finesse, etc. (Pensées, ed. Brunschvicg. 1-4).