Nahum of Gamzu נחום איש גם זו

The Talmud explains the epithet outright: whatever happened to him, he would say "this too is for the good."

The story used to illustrate it runs thus. He was sent with a gift to the emperor — a case full of jewels. On the way, at an inn, the contents were swapped for earth. He saw it in the morning and said: this too is for the good. At court the case was opened, and the gift turned out to be earth; the emperor was enraged. Then Elijah appeared in the guise of one of the courtiers and suggested: perhaps this is the earth of their father Abraham, which, when thrown, turns into swords and arrows. The earth was tried against a rebellious province — and it worked.

What matters here is that the refrain cancels nothing and explains nothing. It is a way of not stopping at the moment when there is no explanation.

That Rabbi Akiva studied with him for twenty-two years is not stated where the famous "this too is for the good" stands: the refrain is in Taanit 21a, and Rabbi Akiva's apprenticeship in Chagigah 12a. The two references are constantly conflated; here they are kept apart.