Srinivasa Ramanujan

The name usually reaches people through the mathematics: mock theta functions and a body of dense identities that later workers had to catch up with. Ramanujan produced results that looked, at first glance, like small clarifications and turned out to sit underneath a great deal of what came after. Colleagues noticed an economy in how he argued — complicated things made handleable in few steps.

He was born in Erode, in the Madras Presidency, in December 1887, and worked as an accountant as well as a mathematician. Reading, correspondence and travel gave him points of comparison for the problems he chose. His work reached publication and demonstration, drew criticism, and was sharpened by the arguing — the disputes forced clearer statements of what his claims covered and where they stopped. Students and collaborators carried the methods into neighbouring areas.

He died in April 1920, at 32. What survives is not only the finished mathematics but the notebooks and drafts, which show how uncertain and provisional the route to that clarity actually was. Institutions have commemorated the work; practitioners have kept revising the techniques with newer tools. Readers who come to him now tend to take away something about attention — the willingness to keep looking at a problem until it yields — as much as any particular theorem.