Wisdom on One Foot
There is a story in the Talmud about a man who comes to Rabbi Hillel and offers to convert if the rabbi can teach him the entirety of the Torah while standing on one foot. Hillel raises one foot off the ground and answers, "What is hateful to you, do not do unto your neighbor; this is the entirety of the Torah. All the rest is commentary. Go study!" There are obvious parallels here to the gospel story of the Sadducee who tests Jesus by asking him which is "the great commandment of the law." Jesus tells him to love God and love his neighbor as himself. "On these two commandments depend all the law and the prophets."
Jesus did not stand on one foot when he gave his answer. But it is clear he and Hillel were drawing on the same source of wisdom. After all, they were near-contemporaries, and both were grounded in Jewish law. I don't know much about Hillel, but the roots of Jesus' teaching ran far deeper than mere religious tradition. This was not fundamentally a teaching about being nice to people. At one point Jesus prays to the Father that his followers "may be one even as we are one, I in them and thou in me, that they become perfectly one..." The commandment about loving your neighbor grows out of the awareness that you and your neighbor are one, and both are rooted in the oneness of God. You must love your neighbor as yourself for the simple reason that your neighbor is yourself.