Hippocrates is a historical as well as a legendary character. In legends he is presented as a personification of the highest intellectual and moral virtues as they were understood by the ancient greeks and romans. One of these legends deals with a fictitious meeting between him and Democritus, the philosopher. We can follow the story in a collection of pseudepigraphic letters from the end of the first christian century. On the behalf of the senate of the city of Abdera Hippocrates takes upon himself the commission to cure Democritus - the eminent son of the city - who is supposed to be mad because he is laughing at everything. However, Hippocrates soon realizes that his commission transcends his medical profession. Democritus is not mad but a very wise man whose yearn for solitude and serenity constrains him to discriminate himself from ordinary people by an odd behaviour. He is a melancholic. In these letters we follow a discussion about moral and medical aspects of madness and the relationship between the noble outsider and his ordinary fellowmen. It is a discussion that points forward at recurrent themes in the history of ideas. Hippocrates stands out as a philantropist and Democritus as a misanthropist.