Jacob Bernoulli (1654-1705), founder of Basel's dynasty of mathematicians, left a relatively small body of correspondence for posterity. Published here for the first time are all 50 preserved letters sent to or by Jacob Bernoulli, and documentary evidence is presented of some l00 further letters no longer extant. The correspondence with Leibniz takes up the bulk of the volume and is also the most substantial scientifically. Topics range from Bernoulli's theories of elasticity and probability, to Leibniz' "Dynamik", to the integration of algebraic functions, to controversies over differential calculus and calculus of variations.