One of the five greatest mathematicians of all time was Leonhard Euler (I would put only Gauss, Euclid, Archimedes, and Newton in his class). An astonishing number of ideas that every mathematically literate person simply takes for granted as background vocabulary were due to him. His collected works comprise some eighty volumes, the bulk of which were written in the last twenty years of his life when he was totally blind! I recommend, without reservation, the following glorious little book:
"Euler, the Master of us All," by William Dunham. That is all.