Thomas Bayes (1702 - 1761) was an English clergyman and mathematician. Until around 1950, he was considered a minor contributor to the history of mathematics, and if he was known at all it was because his name was attached to a simple theorem in the calculus of probabilities. Since then, however, that theorem and the problem Bayes was able to solve with it have become the basis for an important branch of statistical methodology, the problem of inverse probability.