English Explanation of Pirkei Avot 1:1

Moses received the torah at Sinai and transmitted it to Joshua, Joshua to the elders, and the elders to the prophets, and the prophets to the Men of the Great Assembly.
They said three things: Be patient in [the administration of] justice, raise many disciples and make a fence round the Torah.
Avoth begins by tracing the transmission of Torah and contains three sayings by the Men of the Great Assembly.
One of the most basic tenets of Judaism is related in this mishnah: that Moses received an oral as well as a written Torah and that there is an unbroken chain connecting the Rabbis with the revelation at Sinai. Therefore the oral Torah, observed and studied during the time of the Mishnah (and in subsequent generations as well) is not the creation of human beings, but is actually as divine in origin as is the written Torah. Now this an extremely significant claim, about which many, many books have been written, and indeed some fierce battles were fought (such as that between the Sadducees and Pharisees and that between the Rabbinites and Karaites). There are many sub-questions that require further resolution, most importantly what was the nature of the oral Torah received at Sinai. Did Moses receive every detail of observance and belief that any Jew would ever need to know? If so then all of the debates in the Mishnah and Talmud are attempts to recover what was originally known, and for some reason lost (this is Rav Saadiah Gaon’s position). Alternatively, were only the principles given to Moses, and perhaps rules by which later Jews could create new laws, laws that would have roots at Sinai but not have been specified at Sinai? If so, then the Mishnah and Talmud contain actual creativity in advancing and expanding the Oral Torah (this is basically the Rambam’s position).
Needless to say, we don’t have the answer to this question and it has been a great debate since the medieval period. The Talmud itself is unclear on the matter, and there are statements that support both. For instance the Talmud states that even any new innovation taught by a student was already revealed to Moses at Sinai. However, the Talmud also relates a famous story that God showed Moses what was going on in Rabbi Akiva’s study hall and Moses did not understand a word. Nevertheless, one thing is clear from this mishnah. Jewish tradition teaches that the Oral Torah (whether all of the details or just the essence) does come from Sinai and that each generation thereafter is obligated to learn that Torah and transmit it to the following generation.
The Men of the Great Assembly refers to the leaders who arose at the time of the building of the Second Temple, around 500 B.C.E (See Nehemiah 8-10). Little is actually known about this group and there are very few sayings attributed to them. They may have had judicial as well as legislative powers, but again little is known.
In our mishnah three sayings are attributed to them. The first is that judgements should not hastily be delivered. This has also been interpreted to mean that even if a case has come before a judge three or four times before, he must examine it closely perhaps he will find a new angle that he had not before noticed.
Although it may seem obvious that a teacher should seek many disciples, not all Rabbis thought so. Particularly Beth Shammai and Rabban Gamaliel were known for not allowing those whom they deemed disqualified to participate in the discussions in the study halls. This mishnah emphasizes that students should be encouraged to continue to learn, even if he is not perfect.
Making a fence around the Torah is another principle of supreme importance in Judaism. There are many laws that are not strictly obligatory upon a person from the Torah, but rather were instituted by the Rabbis to prevent a Jew from transgressing a Torah law. An example is the use of money on Shabbat. The Torah itself does not prohibit using money on Shabbat. However, the Rabbis said one should not do so, lest one write, which is prohibited by the Torah (at least the midrashic understanding of the Torah).