Five years is the age for the study of Scripture. Ten, for Mishnah. Thirteen, for the obligation to observe the mitzvot. Fifteen, for the study of Talmud. Eighteen, for marriage. Twenty, to pursue [a livelihood]. Thirty, for strength, Forty, for understanding. Fifty, for counsel. Sixty, for sagacity. Seventy, for elderliness. Eighty, for power. Ninety, to stoop. A hundred-year-old is as one who has died and passed away and has been negated from the world.