### COMMUNICATION OF IDIOMS
The term “communication of idioms” (II. *comunicazione degli idiomi*), which etymologically signifies “property” and in common usage denotes one’s native tongue, in philosophical discourse indicates an attribute proper to a nature. The expression “communication of idioms” is employed by theologians in Christology to designate the mutual predication of human and divine attributes in Jesus Christ. The communication of idioms logically follows from the fact that in Christ the divine and human natures are united; indeed, it is nothing other than the logical expression of that ontological communication or union existing in Christ between the human and divine natures and thus between the attributes of one and the other nature.
It is therefore easily understood—and the history of dogma confirms this—that while a vague and indeterminate understanding of the communication of idioms is necessarily accepted by all who acknowledge in Christ the character of God-Man, a more precise and exact interpretation of it is bound up with the manner of conceiving the unity of Christ and the relations in Him between the divine and human natures.
Nestorianism (v.), which divided Christ into two persons united accidentally, admitted the communication of idioms only in the sense that the predicates of one person could be attributed to the other by a moral attribution, in the same way that, in general, the dignity, authority, and honor of a father can morally be referred to his children.
In a direction entirely opposed to this, Monophysitism (v. MONOPHYSITES) moved, which, by fusing the two natures into one, pushed the communication of idioms to the point of attributing to one nature the properties of the other.
Taking a middle path between these two interpretations—of which the first errs by defect and the second by excess—the Catholic doctrine defines the meaning of the communication of idioms as follows:
1) Human attributes can be predicated of the subject Christ when He is denominated according to the divine nature, as in the propositions: “The Word of God, the Son of God, was born in time, had a mother, suffered, died,” and conversely, divine attributes can be predicated of Christ when He is denominated according to the human nature, e.g.: “Christ the man, the Son of the Virgin Mary, the Son of Man, is the Creator of the universe, is begotten from eternity by the Father, is the principle with the Father of the Holy Spirit.” For the hypostatic union implies that Christ is one single “I,” one single person possessing two natures; therefore, the propositions cited above, which establish an identity between the person possessing the properties of one nature and the person possessing the properties of the other nature, are true.
2) On the other hand, however, the dogma of the hypostatic union (v.) implies that the two natures remain in Christ distinct and unconfused; hence it follows that they cannot mutually predicate one another’s properties, nor can the properties of one be predicated of the other. It would be a grave error to affirm that the human nature of Christ is omnipotent, eternal, omniscient; or that the divine nature of Christ is passible, mortal. One would fall into the same error by affirming that Christ, as man, is eternal, or that Christ, as God, died; for such restrictions “as man” or “as God” serve only to indicate in the nature of man or of God the reason for the predicate, and thus such propositions resolve into affirming that one nature possesses the properties of the other, thereby lapsing into Monophysitism.
In conclusion, according to the correct sense established by Catholic doctrine, the mutual attribution of human and divine properties in Jesus Christ does not occur directly between the human and divine natures, but rather between the person denominated according to one nature and the properties of the other nature.
The fact of the communication of idioms is already openly attested in Holy Scripture, as, for example, in the following passages: “And the Word was made flesh and dwelt among us” (Jn 1:14); “The Son of God was made of the seed of David according to the flesh” (Rom 1:3); “Of whom (the Hebrews) is Christ according to the flesh, who is over all things, God blessed for ever” (Rom 9:5); “Who (Jesus Christ), being in the form of God... emptied himself, taking the form of a servant... he humbled himself, becoming obedient unto death, even to the death of the cross” (Phil 2:6-7).
The doctrine of the communication of idioms was solemnly defined by the Church in the Councils of Ephesus and Lateran (Denz.-U., 116, 124, 255). The Fathers, such as Origen, Cyril of Jerusalem, Cyril of Alexandria, and St. John Damascene, developed it in their polemics against Christological heresies; and the Scholastics expressed it in philosophical formulas, precisely defining the laws that must govern our manner of speaking about Christ, among which the most important concerns concrete and abstract nouns.
In a philosophical sense, concrete nouns are those that designate a subject possessing a nature or one of its properties, e.g.: “mortal man,” “corporeal man”; “man” signifies precisely “a subject possessing human nature.” Abstract nouns, on the other hand, indicate only a part, abstracted from the concrete subject in which they are meant to be realized, e.g.: “humanity,” “rationality,” “mortality,” “body,” “soul.” Now the Scholastic rule states that the human nature and its properties can be attributed to Christ the Word when expressed by concrete nouns, but not when expressed by abstract nouns. It is correct to say that the Word of God is corporeal, is mortal; it is false, however, to affirm that the Word is corporeity, is mortality, is a body. This rule finds its justification in the light of the dogma of the hypostatic union, according to which the human nature with its attributes and parts is possessed by the Word, but is not the Word; therefore, the Word is a person who possesses human nature, but is not human nature itself, nor much less its parts and properties.
When, however, it is a question of divine attributes, it is legitimate to predicate them of the person Christ-Man, even when they are expressed in an abstract manner; e.g.: “The Son of Mary is Divinity; He is the Way, the Truth, and the Life.” The reason for this exception lies in the fact that all divine perfections are subsistent, they themselves are the substantial subject, and therefore the nouns that express divine perfections can be taken as concrete nouns.
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### IDIORRHYTHMY
See MONASTICISM, EASTERN.