At five years old a person should study the Scriptures, at ten years for the Mishnah, at thirteen for the commandments, at fifteen for the Talmud, at eighteen for the bridechamber, at twenty for one's life pursuit, at thirty for authority, at forty for discernment, at fifty for counsel, at sixty to be an elder, at seventy for gray hairs, at eighty for special strength (Psalm 90:10), at ninety for decrepitude, and at a hundred a man is as one who has already died and has ceased from the affairs of this world.

Pirkei Avot 5:24