Who is Prince Lev Nikolayevich Myskin from The Idiot and what is their importance?

Myshkin is the main character and the "Idiot" of the title. The main reason they call the Prince an idiot is that he suffers from epilepsy, and the time he spent in a mental hospital has given him little knowledge of the outside world. From the beginning, he displays such openness with people, it prompts laughter in disbelief. In the opening chapter when he makes his way to St. Petersburg, he tells his new acquaintance, Rogozhin, his business in Russia and the problems he has had recovering from his illness without once wondering if Rogozhin is trustworthy.