Pierre Simon Laplace was born at Beaumont-en-Auge in Normandy on March 23, 1749. He died at Paris on March 5, 1827. He was the son of a farm laborer, and owed his education to some wealthy neighbors who were interested and excited by his abilities and engaging presence. Very little is known of his early years. When he became distinguished, he had the pettiness to hold himself aloof both from his relatives and from those who had assisted him.

Pierre-Simon Laplace’s father expected him to make a career in the Church. At the age of 16, Laplace entered Caen University to study theology. However, during his two years at the University of Caen, Laplace discovered his mathematical talents and his love of the subject. Consequently, he left Caen without taking his degree, and went to Paris.

He began producing a steady stream of remarkable mathematical papers. His first paper was on maxima and minima of curves where he improved on methods given by Joseph Louis Lagrange. His next paper concerned difference equations. He quickly wrote papers on the integral calculus, mechanics, physical astronomy, and mathematical astronomy.

Laplace’s reputation steadily increased during the 1770’s. The 1780’s were the period in which Laplace produced the depth of results which have made him one of the most important and influential scientists that the world has seen. It does appear however that Laplace was not modest about his abilities and achievements, and he probably failed to recognize the effect of his attitude on his colleagues. Laplace let it be known widely that he considered himself the best mathematician in France. The effect on his colleagues was only mildly eased by the fact that Laplace was right.

In 1780, Laplace and the chemist Lavoisier showed respiration to be a form of combustion. This work with Lavoisier marked the beginning of a third important area of research for Laplace, namely his work on the theory of heat, which he worked on towards the end of his career.

In 1784 Laplace was appointed as examiner at the Royal Artillery Corps, and in this role in 1785, he examined and passed the 16 year-old Napoleon Bonaparte. He also served on many of the committees of the Académie des Sciences. Laplace was promoted to a senior position in the Académie des Sciences in 1785. Two years later Lagrange also came to Paris. The two great mathematical geniuses, despite a rivalry between them, each was to benefit greatly from the ideas flowing from the other.

Laplace was a member of the committee of the Académie des Sciences to standardize weights and measures in May 1790. This committee worked on the metric system and advocated a decimal base.

In 1795, the Ecole Normale was founded with the aim of training school teachers and Laplace taught courses there, including one on probability. Laplace nowhere displayed the massiveness of his genius more than in the theory of probability. The theory of probability, which Laplace described as common sense expressed in mathematical language, engaged his attention from its importance in physics and astronomy. He applied his theories, not only to the ordinary problems of chances, but also in the causes of phenomena, vital statistics and future events.

The first edition of Laplace’s Théorie Analytique des Probabilités was published in 1812, covering generating functions, approximations to various expressions occurring in probability theory, Laplace’s definition of probability, Bayes’s rule, least squares, Buffon’s needle problem, inverse probability, and applications to mortality, life expectancy, the length of marriages, and legal matters.