Sotah, Chapter 9, Mishnah 9. From this point until the end of the tractate we will deal with things that the Sages abolished over the course of the generations, and with things that changed in the course of history.
The Abolition of the Eglah Arufah:
The Mishnah opens with the abolition of the mitzvah of eglah arufah (the calf whose neck is broken): "Mishe'rabu ha'ratzchanim - batlah eglah arufah" - once the murderers became numerous, the eglah arufah was abolished. Once murderers multiplied, they stopped fulfilling the mitzvah of eglah arufah, since it was no longer possible to say "we do not know who struck him" - there was no longer room for the claim that the identity of the killer was unknown, since there were well known criminals going about who would kill people.
From when? The Mishnah specifies: "Mishe'ba Elazar ben Dinai" - from the time of Elazar ben Dinai, a notorious murderer of those days. The Mishnah adds: "U'Techinah ben Perishah hayah nikra" - that was his original name, and the commentators explain that he would change his name so that people would not be able to know who he was. Once he became known as a serial murderer, "chazru likroto ben ha'ratzchan" - they went back to calling him "the son of the murderer." Just as a person obligated in the mitzvos is called a bar mitzvah - named for the content he carries - so too here he was called "ben ha'ratzchan," one whose very essence is murderousness.
The Abolition of the Waters of the Sotah:
From here the Mishnah moves on to further matters that changed because of the increase in sin: "Mishe'rabu ha'mena'afim - pasku ha'mayim ha'marim" - once adulterers became numerous, the bitter waters ceased. Once adulterers multiplied, the bitter waters of the sotah that she would drink ceased, "ve'Rabban Yochanan ben Zakkai hifsikan" - he was the one who, in his time, toward the end of the days of the Second Temple, put a stop to the use of the bitter waters.
And the reason for this: "she'ne'emar: lo efkod al benoseichem ki siznenah ve'al kalloseichem ki senafnah" - as it says, "I will not punish your daughters when they commit harlotry, nor your daughters in law when they commit adultery" (Hoshea). "I will not punish" - the waters of the sotah do not act and do not test; "your daughters when they commit harlotry" - because harlotry and immorality had become widespread; "nor your daughters in law when they commit adultery" - because they too are guilty of adultery. Once the general situation is such, the test no longer works.
The Gemara clarifies that the intent is not only to actual adultery; even if the case involves relations outside the framework of marriage and between unmarried people, that too is included in this. Once immorality took over, the waters of the sotah are no longer effective.
"Mishe'meis Yosei ben Yo'ezer... batlu ha'eshkolos":
The Mishnah continues: "Mishe'meis Yosei ben Yo'ezer ish Tzeredah ve'Yosei ben Yochanan ish Yerushalayim, batlu ha'eshkolos" - when Yosei ben Yo'ezer of Tzeredah and Yosei ben Yochanan of Jerusalem died, the "clusters" ceased. These are the first of the pairs listed in Pirkei Avos and elsewhere, who were the very beginning of the era of the Tannaim. Once they died, there were no longer people in the world who could be called "clusters."
And the reason for the title: "ish she'hakol bo" - a man in whom everything is found. This is a contracted combination of the words "ish she'kol bo": a person in whom all the wonderful qualities that a person can contain in his character and in his learning were gathered together. Such people no longer existed.
This follows the language of the verse in Michah: "there is no cluster" - and from here comes the title "eshkolos." The idea underlying the verse is that there is no longer a pious and upright man, as the verse continues: "the pious man has perished from the earth, and there is none upright among men." We learn from here that at a certain point in history those people called "clusters" ceased to exist in the world, and the Mishnah teaches that already from their early era - from the death of Yosei ben Yo'ezer and Yosei ben Yochanan - there were no longer people on that level.
In summary: in this Mishnah we learned of three things that were abolished: the eglah arufah, which was abolished once murderers became numerous and it was no longer possible to say "we do not know who struck him"; the bitter waters of the sotah, which Rabban Yochanan ben Zakkai stopped once adulterers became numerous, on the basis of the verse in Hoshea; and the "clusters" - those people "in whom everything was found" - which ceased when Yosei ben Yo'ezer of Tzeredah and Yosei ben Yochanan of Jerusalem died.
In what follows we will continue to deal with the rest of the things that were abolished and that changed over the course of the generations, until the end of the tractate.