There is a biblical basis to the idea of the existence in man's nature of an instinctive tendency or impulse (yeẓer as in Ps. 103:14 from yaẓar, i.e., to "form" or "create" as in Gen. 2:8), which, left to itself, would lead to his undoing by prompting him to act in a manner contrary to the will of God (whence the term yeẓer ha-ra or "inclination to evil"). Thus, in Genesis 5 it is stated that "every inclination of the thoughts of his – i.e., man's – heart is only evil continually" and again in Genesis 8:21 "for the inclination of man's heart is evil from his youth." The doctrine of the two inclinations (or drives) is a major feature of rabbinic psychology and anthropology. As a personification of the permanent dualism of the choice between good and evil, the rabbinic notion of the two inclinations shifts this dualism from a metaphysical to a more psychological level (i.e., two tendencies in man rather than two cosmic principles). According to the rabbis, man was created with two opposing inclinations or tendencies, one impelling him toward the good and the other toward evil. This, in their opinion, was indicated by the employment in the term Vayyiẓer used in regard to man's creation in Genesis 2:7, of two yods (Ber. 61a). However, even the so-called yeẓer ha-ra, which corresponds roughly to man's untamed natural (and especially sexual) appetites or passions, is not intrinsically evil and, therefore, not to be completely suppressed. Without it, a human being would never marry, beget children, build a house, or engage in trade (Gen. R. 9:7). It is only when it gets out of hand that it becomes the cause of harm. An effective antidote is the study and observance of Torah (cf. Kid. 30b). This would suggest that the Torah is conceived as an ordering, guiding, and disciplining principle with regard to the untamed natural urges. While the yeẓer ha-ra is created in man at birth, the yeẓer ha-tov, which combats it, first makes its appearance 13 years later at the time of his *bar-mitzvah, i.e., when one assumes the "Yoke of the Torah" and with the onset of the age of reflection and reason (cf. Eccles. R., 4:13, 1). Unless it is checked and controlled, the yeẓer ha-ra will grow like habit. At first it resembles the thread of a spider's web but at the end it is like the stout rope of a wagon (Suk. 52a). Another parable describing the yeẓer ha-ra is that of a wayfarer who starts out by being taken in as a guest and ends by making himself the master of the house (ibid. 52b). Greatness does not necessarily render a human being immune from the power of the yeẓer ha-ra, which manifests itself in such traits as vindictiveness and avarice (Sif. Deut. 33), anger (Shab. 105b), and vanity (Gen. R. 22:6). In fact, the greater the man, the stronger are such tendencies apt to be in him. The yeẓer ha-ra operates only in this world. It does not exist in angels or other spiritual beings (Lev. R. 26:5). "In the world to come," said the amora *Rav, "there is no eating or drinking, procreation or barter, envy or hate" (Ber. 17a). The yeẓer ha-ra has been personified by being identified with Satan, man's tempter in this world and his accuser in the world to come, and also with the Angel of Death (BB 16a; cf. Suk. 52b). In Genesis (3:1ff.) the serpent is presented as man's tempter. Whether the devil, Sammael, merely employed the serpent as an instrument of himself assumed the form of a serpent is not clear from the text of the Greek Apocalypse of Baruch.
Porter, in: Biblical and Semitic Studies… Essays… (1901), 91–156; G.F. Moore, Judaism…, 1 (1927), 479–93; S. Schechter, Some Aspects of Rabbinic Theology (1936), index; C.G. Montefiore and H. Loewe, Rabbinic Anthology (1938), index S.V. Evil Inclination. ADD. BIBLIOGRAPHY: S. Klein-Braslavy, Maimonides Interpretation of the Adam Stories in Genesis (A Study in Maimonides' Anthropology) (1986), 212–17 (Heb.); B. Braun, "True Will, or Evil Inclination: Two Ḥaredi Thinkers' Concept of Freedom," in: Hagut, 1 (1998), 97–125 (Heb.).