Philo of Alexandria in Legum allegoriae II, 79-81 interprets the bronze serpent of Num 21, 4-9 as *logos sophrosunes* ("character of temperance"). The snake in LA II, 79-81, as *ophis Euas* ("serpent of Eve"), on the one hand, is the vice, but on the other, as *ophis Mouses* ("serpent of Moses"), is the image of virtue. Philo considers the snake of Numbers according to both the ethical and the noetical level. As *logos sophrosunes* the bronze serpent corresponds to the intelligible virtue. It is the *idea* ("idea") that must be looked at so that we can have a moral model to imitate, to eliminate every vice. The mosaic snake, like an ethical and noetical mirror, shows a new possibility for the Israelites to embrace the faith in the sign of temperance. The exegesis of Philo of Num 21, 4-9 is imbued with elements of the Greek-Roman World and the Jewish Tradition. His exegesis returns back in the interpretation of some ecclesiastical authors, that considered the snake of Numbers in relation to Jn 3, 14-15. Authors like, Tertullianus, Origenes, Gregorius Nazianzensus, Gregorius Nyssenus and Ambrosius, largely repeat the ethical and pharmacological aspects of his exegesis. Furthermore, the interpretation of Philo leaves a trace in the Physiologus and in the fantastic imagination of the medieval bestiaries, in which animals become moral models to follow. Over the centuries the intelligible character of the bronze snake of the Philonian exegesis will not be recalled again, which thus remains an innovative and isolated interpretation. The interpretation of Philo has contributed to the development of the ethical and pharmacological character of the mosaic snake. Moreover, it fostered the positive image of the snake, that divided between good and evil, becomes the representation of temperance as moderation. To look at the *sophrosune* means to avoid the vice and to embrace the virtue.