Sign

SIGN. - In a broad sense a sign (Gr. σημεῖον) is anything (reality, image, object) that manifests another: «quodcumque notum in quo aliquid cognoscatur» (St. Thomas, De verit., q. 9, a. 4 ad 4; cf. Sum. Theol., 3ª, q. 60, a. 4: «signum est per quod aliquis devenit in cognitionem alterius»): thus breathing and the beating of the heart are signs of life. In a stricter sense, a sign is that which exists, or is assumed, solely as the expression of another thing: in this sense the flag is a sign of the homeland, the word a sign of the idea.

Lalande (Vocab. techn. et crit. de la philos., 5th ed., Paris 1947, pp. 970-71) proposes a threefold distinction: a sign is: 1) a present perception that permits, with greater or lesser certainty, an affirmation relative to another thing: in this sense it may be said that the extension of the sign is very broad, on account of the multiplicity of relations that connect the various aspects of a reality and the different realities among themselves; 2) an act or gesture expressive of a command or of an action to be performed; 3) an object (figure, image) that serves exclusively as a symbol of another thing and recalls its representation or idea, e.g., the symbols of the chemical elements: this is the sign in the strict sense already defined. The further distinction of the sign into natural and conventional is founded on the nature of the relation that obtains between the sign and the thing signified: «natural» is the sign that involves a real relation (of cause, effect, resemblance: where this last relation intervenes, one sometimes speaks of a «formal» sign, and in this sense the concept is called a «formal» sign as the representation or intentional form of the object: cf. St. Thomas, De verit., loc. cit.), e.g., the imprint indicating the passage of an animal and its direction, or the various physiognomic signs as the expression of feelings and psychic qualities (a semantics already attempted, empirically, by Aristotle: cf. Physiognom., especially ch. 3). If, on the other hand, the relation between the sign and the thing signified is brought into act by pure convention, the sign is «conventional», e.g., the signs of musical language. The division is by extremes and admits of intermediate degrees, inasmuch as in some objects there may be a certain aptitude to be assumed as signs of a determinate thing, e.g., the scales as a sign of justice or, in the Christian religion, Baptism as a sign of inner spiritual purification. As regards human language, it may be said that it comprises all the gradations of the semantic relation, from the cry, the immediate expression of a feeling, to onomatopoeic or structurally and phonetically expressive words, down to the purely conventional and arbitrary ones of modern scientific languages.

The meaning of the sign is relevant in human knowledge, not only practical, where its function is very well known, but also theoretical. Already Aristotle noted its philosophical importance, inasmuch as «it is proper to philosophy to be able sometimes to discover something necessary where certain signs present themselves» (Physiognom., ch. 2, 807 a 9-10). In reality, understanding the sign in its broadest meaning, it is through sensible signs (the exterior characters of the world and of its activity, revealers of contingency) that it is possible, for St. Thomas, to arrive at the affirmation of God. It is St. Thomas's own observation «quod signa proprie dantur hominibus quorum est per nota ad ignota pervenire» (Sum. Theol., 3ª, q. 60, a. 2, c.; cf. De verit., loc. cit.). It is therefore perfectly consonant with the character of human knowledge and activity that supernatural reality and its communication to man be expressed in the Christian religion through sensible signs (Sacrifice, Sacraments).

Ugo Viglino