On the individual level, we have the teaching of Rabbi Abahu, who said, 'Where baalei teshuvah stand, people who have never sinned cannot stand!" (Berachot 34b). One who has been broken, so to speak, and then put himself back together again has proven his strength in a way that cannot be claimed by one who has not been put to the same test.
For the nation at large, the antifragile nature of Jews is illustrated by Vehi She'amda in the Haggadah:
And it is this that has stood for our Forefathers and us. For not just one enemy has stood against us to wipe us out. But in every generation there have been those who have stood against us to wipe us out, and the Holy One Blessed Be He saves us from their hands.
What is this in the passage? To put it in grammatical terms, it is a pronoun with no antecedent. Some say what is referenced is the covenant that G-d originally made with Avraham. But it is also possible to read the "this" as referring to what follows -- the persecution itself. With each bout of persecution, the Jews grow stronger.
We see that manifestations of antifragility as early as the Egyptian enslavement. The more the Egyptians oppressed the Israelites, the more they multiplied. In fact, Chazal observe that the Levites did not grow in population as much as the other tribes precisely because they were not subjected to slave labor.
Centuries later, it was the very threat of annihilation that the Jews faced under the regime of Achashverosh that occasioned their triumph over their enemies and a renewal of the acceptance of Torah that gave rise to the flourishing of Oral Torah.
In fact, the situation the Jews faced in the original Purim story is paradigmatic for their spiritual survival. Chazal (Sanhedrin 97b) say that if G-d sees the Jewish people constantly transgress the laws of the Torah and do not repent, He will bring a king to power whose decrees are like those of Haman. Then the nation will be forced into becoming ba'alei teshuvah ansd so gain the merit to be saved.
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