Blaise Pascal (June 19, 1623 – August 19, 1662), mathematician and philosopher, was educated at home by his father, himself a considerable mathematician. The origins of probability are usually found in the correspondence between Pascal and Fermat where they treated several problems associated with games of chance. The letters were not published but their contents were known in Parisian scientific circles. Pascal's only probability publication was the posthumously published Traite du triangle arithmetique (1654); this treated Pascal's triangle with probability applications. Pascal introduced the concept of expectation and discussed the problem of gambler's ruin.