Rabbi Hillel was one of the great heroes of the Jewish People. He served in a position that combined religious and secular leadership, and was the highest position of leadership in Jewish Society during the several centuries preceding and several centuries following the destruction of the Second Temple. Hillel himself lived at the beginning of the century preceding the Destruction.
In addition to his contributions to the understanding of Jewish Law, he is famous for a number of incidents in his personal life, and "ethical" pronouncements that he made:
Most famous perhaps is the incident which occurred before his rise to leadership, when he was not yet a scholar, but had a burning desire to study Torah. At that time, Torah study was tightly controlled and limited only to those of the highest caliber and to those who could pay for it. Hillel, working then as a woodchopper, did not have enough money to pay for entry into the Beit Midrash. On a freezing cold snowy day, he climbed onto the roof of the Study Hall, and lay at the "skylight" listening to the lecture, until he froze. When the scholars below observed his form above, they retrieved him, and changed the policy such that anyone who wished to study Torah could come in and do so.
A certain non-Jewish "wise-guy" came to scoff at the Torah, first to the home of Shammai, then to the home of Hillel. He said, "Teach me the Torah while I am standing on one foot." Shammai, sensing his true intention, had him thrown out forthwith.
When the individual came to the home of Hillel with the same request, Hillel responded. "No problem! The main idea of the Torah is 'Love your neighbor as yourself.' Everything else is commentary. Now, if you're really interested, go and study the commentary." So impressed with Hillel's response, according to Jewish Tradition, was the visitor, that he took Hillel up on his instructions, began to study the Torah seriously, and became a Jew.
Source: http://rabbihillel.com/This final quote which grows out of the same theme:
"What is hateful to you, do not do to your fellow;
that is the whole Law; all the rest is interpretation."