  In the summer of 1654, Pascal returned briefly to mathematics in correspondence with Pierre Fermat (1601–65) about calculating probabilities associated with gambling. He summarized his findings in the Traité du triangle arithmétique which, like much of his other work, remained unpublished until after his death. In fact, as Edwards explains (Hammond, 2003: Chapter 3), Pascal's contribution to probability theory was not recognised until it was used by Bernoulli in the early eighteenth century.