If you are interested by the personalities behind mathematics, or simply in the peculiar mind of a genius, it is worth reading Bruce Schechter’s book on Paul Erdős (well, with my Hungarian background I should really write Erdős Pál). Erdős Pál was undeniably one of the greatest scientific minds of the 20th century and certainly one of the greatest mathematicians ever. But also a very peculiar personality. He lived a completely “monastic” life; he never had a fixed job, a place he could really call “home”, all his worldly possessions would fit into a suitcase, and he spent most of his life traveling around the globe from one conference to the other, from one city to the other, wherever he had friends he could do mathematics with. He was author or co-author of around 1,500(!) articles; the number of collaborators was so big that the community came up with the humorous notion of “Erdős number”. He was also incredibly generous in helping young, talented mathematicians to start their career.
I did not have the pleasure to meet Erdős personally, although I had the privilege of having some of his closest collaborators as my teachers at the University of Budapest in the early 70’s (Turán, Sós, Simonovits, Hajnal,…). But he regularly came back to Hungary. We never knew when (nobody did, in fact); the news suddenly spread among us that Erdős was in Budapest and that he would make a presentation, well, tomorrow afternoon. And we went, forgetting our regular, scheduled courses and listed to his talk. His lectures were always great, witty, and full of interesting and unsolved problems. He would usually come with a problem saying “this seems to be an open issue, I have the feeling that it could be solved this and this way; I give a prices of 100$ to whoever solves this”. Or $10 or $1,000, depending on the problem (although the monetary side was not the most important in trying to solve those problems; the perspective of gaining an Erdős number 1, ie, becoming one of Erdős’ co-authors, was much more of an incentive). Even if our field of interest did not coincide with Erdős’, these lectures were always among the highlights of the year. And it did not occur often; I think in those 5 years that I spent at the University, I saw him twice, or maybe three times… certainly not more.
It may be an unusual analogy, but his personality, and the style of his appearances remind me of another genius in a totally different area, namely Sviatoslav Richter. Much like Erdős, he was one of the greatest personalities of the century in a particular field (as a classical pianist) who also led a kind of a recluse, monastic life without real possession and ignoring all traditional signs of success. And much like Erdős nobody knew when he would appear in Budapest for a concert nor what he would play; the news spread among those interested and we all ran to listen to his performances (played in a darkened concert hall, with barely a small lamp on the piano illuminating the music sheet only). And his performance of Bach’s Well Tempered Clavier remain among the most cherished memories I have from my youth. Much like Erdős’ occasional visits.
A book worth reading.
 Bruce Schechter: “My Brain is Open, the Mathematical Journeys of Paul Erdős”. The book is not new, but just appeared on some airports, that is where I found it…