Joseph Dauben

Long biography, read in hopes of reducing my woeful ignorance of nonstandard analysis, which provides a way of viewing and using infinitesimals as legitimate numbers. E.g., the values of a function's derivative really *can* be treated as ratios of two differentials, sidestepping the standard limit (epsilon-delta) constructions. Newton and (especially) Leibniz (who gave us the dy/dx notation), facing the carpings of George Berkeley and his ilk, would have been thrilled.

Neither a biography of Cantor nor a study of transfinite numbers, but rather the intellectual history of a mathematical idea as seen from the personal life of its main proponent.

The complete deal -- definitive.