It might come as a surprise that there was no one in the entire generation of Ben Azzai who could create souls of converts. After all, what about Rebbi Yishmael ben Elisha Kohen Gadol, who we said was a spark from the soul of Joseph Hatsadik/Joseph - why did he not possess such an ability?

...the punishment of Rebbi Yishmael was the most difficult of all...

The answer has to do with what we spoke about earlier regarding the ten martyrs, that they were the ten seed-drops that left Joseph. Since Joseph himself sinned (and came back as) Rebbi Yishmael, for those seeds went to the depths of the kelipot. Therefore he lacked the ability to make souls of converts. Hence we find that the punishment of Rebbi Yishmael was the most difficult of all the ten martyrs, since he was the cause of their deaths, through the seed that was emitted.

Thus, that which is written with respect to Joseph, "they removed Joseph’s coat from him" (Gen. 37:23) is similar to what it says about Rebbi Yishmael, that the skin of his face was removed. Also, Rebbi Yishmael is compared to Joseph, in as much as they were both very handsome (Gen. 39:6) as it says in Pirkei Heichalot.

In addition, just as Joseph was held captive among the Egyptians, so too was Rebbi Yishmael held captive. It says that when Rebbi Yehoshua ben Chananyah asked, "Who gave Jacob up for spoil?" (Isaiah 42:24) he (Rebbi Yishmael) answered him, "Was it not God, against lo [He] Whom we sinned?" (Ibid, Gittin 58a)

...the sparks of the seed-drops of Joseph which fell down to the kelipot in the place of the legs...

In saying "lo" [he], he was making an allusion: Because of the sin of the sparks of the seed-drops of Joseph which fell down to the kelipot in the place of the legs,1 he himself was exiled among the gentiles. This is what he meant by, "Who gave Ya’akov up for spoil" - that is the drops. He answered him, "Was it not God, against He Whom we sinned?" (including himself).

"Lo"/LV is gematria 36, which is 6 squared. Yesod is the sefira of the covenant. From it comes male/female connection. It is the soul root of Joseph, therefore was he tested in such issues. Primarily he withstood the test and is so called ‘tsadik’ par excellance because of it. Nonetheless, there still was as if some slight defect that happened at the time of his test with the wife of Potifar. (Gen. 39:7-13) Because of his colossal spiritual plateau, it had to undergo rectification.

Yesod is the sixth sefira. It binds the six directions/days and reveals them as one unified arena through which Divinity to manifest. Six squared represents the spreading out of yesod in all glory to all of its facets. Joseph, the king of yesod, was required to fix it to the fullest. Hence Rebbe Yishmael,2 the one through whom the repair took place, voiced this through "lo"/36.

[Translation and commentary by Perets Auerbach.]