On the "Golden Rule"
Once there was a gentile who came before Shammai, and said to him: "Convert me on the condition that you teach me the whole Torah while I stand on one foot. Shammai pushed him aside with the measuring stick he was holding. The same fellow came before Hillel, and Hillel converted him, saying: That which is despicable to you, do not do to your fellow, this is the whole Torah, and the rest is commentary, go and learn it." - Babylonian Talmud, Shabbat 31a
If Not Now, When?
If I am not for myself, then who will be for me? And if I am only for myself, then what am I? And if not now, when?
On Time for Study
Do not say: When I have leisure I shall study, perhaps you will never have leisure.