These words are variously rendered in our Bibles, and they really have different senses according to the context and application; but there are certain distinctions invariably maintained between them, although these are not accurately represented by the ordinary uses of the English terms “soul” and “spirit.”

It will be found that נֶפֶשׁ and ψυχη very closely agree together, both being derived from verbs (נפשׁ and ψίχω) which primarily signify to breathe (see Job xli. 21 [13]) as a sign of life, and frequently referring to the refreshing coolness of air in gentle motion. These two words therefore denote the animating principle which distinguishes active creatures. Yet they do not mean simple vitality, for neither of them is ever applied to plants; but נֶפֶשׁ at least is occasionally spoken of a human corpse as having been the seat of life. Again they do not denote incorporal beings, for they are never used of angels nor (except in a few phrases where they are equivalent simply to self) of God (as figuratively of Sheol, Isa. v, 14). They are both nomena, applied indifterently to human beings and to animals.

On the other hand רוּחַ and πνεῦμα are equally allied to each other, both springing from roots (רוּחַ and πνέω) signifying to blow, and often used literally of wind or an inviolent motion. They are regularly spoken of angels (whether good or bad) and of God, but are never applied to beasts except in very few passages (Gen. vi. 17, vii. 15, 22; Ps. civ. 29 ; Eccles. iii. 19, 21) by way of Zeugma with man.

It thus appears that these two sets of words properly represent respectively the lower order of animated creation and the higher range of intellectual and moral beings. In as much as man partakes of both these elements, having a vital, moving, sensitive body, as well as a consciously rational and accountable soul, he may appropriately be designated by either of them, as viewed from the animal or spiritual side. Accordingly we find them applied almost indiscriminately to him as a living sentient being. The sacred writers do not nicely distinguish, at least by their use of these terms, between his different faculties, although נֶפֶשׁ and ψυχη seem to point more or less directly to the passions and emotions which characterize him bodily and personally, while רוּחַ and πνεῦμα relate rather to those trials which befit him mentally and morally. In a few passages (especially of the New Testament, e. g. 1 Cor. XV. 45; 1 Thes. v. 23) this line of demarcation is somewhat sharply defined; and in the adjective forms ψυχικός and πνευματικός a similar distinction appears, but is usually turned in the Christian direction of the natural as opposed to the regenerate state, once (1 Cor. xv., 44) of the body as subject to a kindred change in the resurrection.