From Quora : "Alexander Grothendieck was (is) a genius of the first order, and a truly amazing spirit. Freeman Dyson once categorized mathematicians as being of roughly two types: birds and frogs. The latter group studies the fine details of the terrain; the former group soars high above and surveys the landscape. Grothendieck was the highest-soaring bird — to Grothendieck, a problem was not truly solved until it was viewed from the "right" general perspective, from which it could be solved effortlessly, from which it became in a sense obvious, from which it fit naturally into a larger conceptual framework. " and more.