The Forgotten Rashba
Torah learning
Rav Noach knew the whole Rashba thoroughly. It is told that during a shiur he presented a chiddush, and one of the talmidim cited a Rashba that did not fully agree with it.
As soon as he heard the words of the Rashba, Rav Noach realized that he had overlooked it and forgotten it. The pain and anguish of having forgotten the words of the Rashba were so great that he fainted.