Grothendieck

... never heard of the man before in my life. He received a Fields medal in 1966, that's roughly equivalent to a Nobel Prize for mathematics. Silly me.

"...The mere enumeration of Grothendieck 's best known contributions is overwhelming: topological tensor products and nuclear spaces, sheaf cohomology as derived functors, schemes, K-theory and Grothendieck-Riemann-Roch, the emphasis on working relative to a base, defining and constructing geometric objects via the functors they are to represent, fibred categories and descent, stacks, Grothendieck topologies (sites) and topoi, derived categories, formalisms of local and global duality (the 'six operations'), étale cohomology and the cohomological interpretation of L-functions, crystalline cohomology, 'standard conjectures', motives and the 'yoga of weights', tensor categories and motivic Galois groups. It is difficult to imagine that they all sprang from a single mind. ..."

It looks as though I haven't got a clue to what mathematics ( algebra ) is about. It is however possible that the concepts are in my mind that I only have to match the words. Like with groups and rings. Once you understand the concept it becomes so trivial that you think you have always known what a group was, or a Galois group for that matter.