Why does Elisha's discussion with Charicles deeply disturb Elisha?

Elisha is deeply disturbed by his discussion with Charicles because Charicles proposes that the basis for Elisha's pursuit of knowledge could be false. No one in Elisha's life, including himself, has ever called into question these ideas, which he has always excepted as absolute truths. Elisha feels like a failure, after devoting his life to study based on ideas he now questions.