In this, his most famous work, Pierre-Simon, Marquis de Laplace lays out a system for reasoning based on probability. The single most famous piece introduced in this work is the rule of succession, which calculates the probability that a trial will be a success based on the number of times it has succeeded in the past. Students of mathematics will find A Philosophical Essay on Probabilities an essential read for understanding this complex field of study and applying its truths to their lives. French mathematician PIERRE-SIMON, MARQUIS DE LAPLACE (1749-1827) was essential in the formation of mathematical physics. He spent much of his life working on mathematical astronomy and even suggested the existence of black holes. Laplace is also known for his work on probability.