His son Shim'on used to say: All my life I have grown up among the sages and I have found nothing to be of greater physical benefit than silence. It is not the study which is essential but the performance. The more you say the more you sin.
1:
Clearly, the sage of our present is Rabban Shim'on ben-Gamli'el. However, as you may recall, within the time-frame that is represented in Tractate Avot there were two sages bearing that name. The first died a violent death during the great war against the Romans, around the 68 CE; the second was active during the period after the collapse of the Bar-Kokhba revolt in the middle decades of the second century CE. There does not seem any reason to assume that the sage of our mishnah is not the Rabban Shim'on who was the son of the Rabban Gamli'el who was the sage of the preceding mishnah.
2:
Rabban Shim'on ben-Gamli'el was a very courageous person and assumed a position of leadership during the revolt against the Romans. Even though Josephus was his bitter opponent, the renegade historian has to admit that Rabban Shim'on was the kind of leader who would have brought the revolt to a successful conclusion had he survived. (In the early months of the revolt Josephus obviously aspired himself to become the leader of the insurgents; his chances in achieving this aim became very dim when Rabban Shim'on ben-Gamli'el made common cause with a Sadducean leader, Anan, an ex-high priest. It is not clear whether this was intended to unite all the people into one war effort or whether it was a political gambit to block Josephus.) According to the minor tractate Evel Rabbati, Rabban Shim'on ben-Gamli'el was done to death by the Romans (and thus became one of the "Ten Martyrs" of whom we read during the Musaf service on Yom Kippur). However, another view, that he was assassinated by fellow insurgents who objected to his moderation in the prosecution of the war, is also highly likely.
3:
We can, perhaps, gain some picture of the man by looking at the way on one occasion he dealt with a peace-time economic problem. Women who had given birth were required to bring to the Bet Mikdash a pair of doves as a thanksgiving offering. It seems that most women 'saved up' these offerings and brought several for several births during one visit to Jerusalem – probably when the whole family spent a festival in the Holy City. As we learned when we studied Tractate Tamid, in the main esplanade of the Bet Mikdash was a market place where, for the sake of convenience, people could buy the creatures that were to be sacrificed. The Mishnah [Keritot 1:7] tells how on one occasion unscrupulous merchants raised the price of these birds inordinately; thus a woman who had to bring several sacrifices for several births was in a very difficult economic situation. And, of course, this artificial raising of the prices was grossly unfair and unethical. Rabban Shim'on ben-Gamli'el decided that the only way to right the situation was to hit these merchants where it hurt them most: in their pockets. "I swear," he said, "that I shall not go to bed tonight before the price will be reduced." He went into the Bet Midrash and stated that from now on a woman who had five successful births (for example) need only bring one pair of doves which would cover all her births and she would not have to repay any of the others at some later stage. By the end of the day the bottom had fallen out of the dove market and the cost of a pair of doves was reduced by 75%.
4:
He also seems to have been quite an athletic man. The Gemara [Sukkah 53a] records that during the merry-making during the festival of Sukkot
he would juggle with eight burning torches and not one of them fell to the ground, and when he prostrated himself he placed his finger upon the pavement, bowed, kissed the ground, and immediately stood upright.
5:
From the historical point of view we should probably best understand the first clause of our present mishnah as reflecting the personal policy of circumspection that Rabban Shim'on ben-Gamli'el must have adopted during the turbulent years of the great revolt. When the infighting among the rebel leaders was quite internecine it must have made great sense for one of the leaders to adopt a policy of "least said soonest mended". If this was his reason for adopting a posture of silence it was not of ultimate "physical benefit" to him since, as mentioned above, he was eventually done to death either by his fellow insurgents or by the Romans.
To be continued.