The number 40 has great significance throughout the Torah and the Talmud. The number 40 represents transition or change; the concept of renewal; a new beginning. The number 40 has the power to lift a spiritual state.
In the Bible, next to the number seven, the number forty occurs most frequently. In Talmudical literature it is often met with, in many instances having been apparently used as a round number or as a concrete and definite expression in place of the abstract and indefinite “many” or “some,” and hence becoming a symbolical number. As regards the period of forty years, the Jews seem to have shared with other peoples, especially the Greeks, the notion that the fortieth year was the height or acme of man’s life; and from this fact forty years came to represent a generation (compare Nöldeke, “Untersuchungen zur Kritik des Alten Testaments,” p. 188).