משנה מסכת אבות פרק א משנה א
משה קבל תורה מסיני ומסרה ליהושע ויהושע לזקנים וזקנים לנביאים ונביאים מסרוה לאנשי כנסת הגדולה הם אמרו שלשה דברים הוו מתונים בדין והעמידו תלמידים הרבה ועשו סייג לתורה

1. Be deliberate in judgment. – הוו מתונים בדין – Think carefully before making decisions. Don’t be rash.
2. Raise up many students – העמידו תלמידים הרבה – Don’t hide one’s thoughts from others. The goal of studying and learning and living is to impart one’s knowledge and experience to the next generation.
3. Make a fence around the תורה – עשו סייג לתורה – Following the simple law is not enough. It is easy to make mistakes if one isn’t careful. Therefore build fences, but remember what you’re fence is guarding. If you don’t understand why you are stringent about something, you could just as easily let your guard down.

How do these relate three things relate to each other?

אנשי כנסת הגדולה, the transitional body from the time of נביאים to the time of Rabbis, is providing a certain series of principles to carry the nation forward. They were the leadership during the early years of בית שני. While historians are unsure as to how long this organization lasted, suffice it for now to assume we are dealing with a group that lasted until some time during the Greek/Hellenism period. As the transitional group from the prophets, they had a simple goal, the need to train halachic decisors and leaders for the future. To do this, they recommended three steps.

1. Be deliberate in judgment. Since we no longer can rely on direct communication with G-d, whether through נביאים or through the אורים ותומים (which were hidden before the destruction of the first Temple), we must rely on our own judgment. Therefore, be careful with making decisions. Decisions have consequences and the chance for mistake is greater. One must be slow and methodical, making sure to check as much as possible before making the best decision possible.

2. Raise up many students. As part of being deliberate, don’t be quick to drive people away. Give everyone a chance. The goal is to raise up students who can be the future of the Jewish nation. Since the teacher is not all-knowing, one can never know who might be the leader. Therefore, raise many students and don’t abandon anyone before giving the person the chance to succeed. Also, the raising of many students assures the greater chance for survival of the system of oral law.

The use of the word raise and opposed to teach is important to highlight. The goal is not just to teach students but one also needs to raise students to become teachers. Knowledge alone is not the only goal of making many students.

3. Make a fence around the תורה. The final step in strengthening Judaism, helping it survive the change, is to guard the תורה, done through actively setting up guard posts. Some of the guard posts are changes, such as תפילה, which eventually replaces sacrifices as the mode of worship. However, realize that making fences around the תורה is not the same as adding new laws. The making of a fence, in a literal sense, is that we put up a structure to surround another structure. This makes the fence integral to the survival of the structure, yet the structure is still the main focus. Similarly, in the case of תורה, the true fence is when we can remember the original law and know why the additional stringencies were added. This is not like divine law, which Israel accepted נעשה ונשמע, by doing and asking questions later. This is the establishment of “man-made” law, which needs to be understood because without understanding, it will be easier to simply say, its not G-d’s law, therefore we don’t need it.

Therefore, the simple explanation is that אנשי כנסת הגדולה believed that to keep Judaism alive, we need fences around the law, handed down by one’s students, who then become the next generation of teachers, and which are determined by careful deliberation. Random stringencies and decisions without slow judgment can lead to utter neglect.