Who said if not now when?

"If not now, when?" is part of a saying of Rabbi Hillel ("Hillel the Elder"), first century BCE, recorded in a section of the Talmud (Jewish Holy writings) called "Pirkei Avot" ["Ethics of the Ancestors" or "Ethics of the Fathers"]. The complete saying is: "If I am not for myself, then who will be for me? When I am for myself only, what am I? If not now, when?" (Pirkei Avot 1:14)