Acharya Prashant discusses the vulnerability and invincibility of Howard Roarke, a character from 'The Fountainhead', in the context of being tricked by Ellsworth Toohey. He explains that Roarke's innocence and absolute strength make him superficially vulnerable because he feels no need to learn the wiles and guiles of the world. Roarke is so secure in his center that he does not take care to secure himself against external traps. This lack of worldly cleverness allows someone like Toohey to play tricks that lead to Roarke's financial bankruptcy or defamation, yet these external defeats do not displace Roarke from his inner center. Acharya Prashant compares this dynamic to that of a sage or a rishi. While a common man is clever and knows all the tricks because he plays them himself, a sage is in a sense foolish regarding worldly matters. A common bully or rowdy could easily fool or cheat a sage like Ashtavakra because the sage does not bother with self-protection. However, the speaker emphasizes that while the worldly man might win the initial rounds through cleverness, the sage remains unbeatable because his essence cannot be broken. Innocence, therefore, creates a contradiction where one is both highly vulnerable to external harm and deeply invincible in character.