Brilliant? Yes. Crazy? Yes.

Masha Gessen, who visits from Moscow on 3/8, answers questions on the Amazon website about her 2009 biography of Grigori Perelman, the eccentric Russian genius who solved the Poincare Conjecture, perhaps the most important mathematical achievement of the last century.

Q: So he is as crazy as they say?

A: I think crazy generally means that a person has an internally consistent view of the world that is entirely different from the view most people consider normal. I think this is true of Perelman. The interesting thing, of course, was to figure out what this internally consistent view of the world was.

Q: And did you manage to figure it out?

A: I think so. I concluded that this view, and the rigidity with which he holds to it, is actually directly related to the reason he was able to solve the hardest mathematical problem ever solved. He has a mind that is capable of taking in more information, and embracing more-complex systems, than any mind that has come before. His mind is like a universal math compactor. He grasps hugely complex problems and reduces them to their solvable essence. The problem is, he expects the world of humans to be similarly subject to reduction. He expects the world to function in accordance with a set of strictly laid out rules, and he absolutely cannot take in anything that does not conform to those rules. The world of humans is unruly, though, so Perelman has had to cut off successive chunks of it until all that was left was the apartment he shares with his mother.