Pierre Guillaume Frédéric le Play (; April 11, 1806 – April 5, 1882) was a French engineer, sociologist and economist. Life The son of a custom-house official, Le Play was educated at the École Polytechnique and the École des Mines. He took an interest in sociological questions even as a young man at the École des Mines, befriending a follower of the socialist thinker Saint-Simon. In the late 1820s, Le Play undertook an immense walking tour of Germany investigating its mines. In 1830, a laboratory accident seriously damaged Le Play's left hand and left him disabled for life. While he was recovering in Paris, he was a witness to the events of the July Revolution, and thereafter resolved himself to studying the issues that plagued French society. In 1834, he was appointed chairman of the permanent committee of mining statistics. He spent the remainder of the 1830s traveling the backroads of Europe as a mining expert, and conducting empirical studies on the state of mines and their workers. In 1840, he became engineer-in-chief and professor of metallurgy at the École des Mines, and was made inspector in 1848. In the 1840s he also became the manager of a mining company in the Ural Mountains. During this time he also met with many of France's leading thinkers and politicians, including Félix Dupanloup, Alphonse de Lamartine, Charles Montalembert, Adolphe Thiers, and Alexis de Tocqueville, to discuss social issues. For nearly a quarter of a century Le Play travelled around Europe, collecting a vast amount of material bearing on the social and economic condition of the working classes. In 1855, he published Les Ouvriers Européens (The European Workers), a series of 36 monographs on the budgets of typical families selected from a wide range of industries. This work was crowned with the Montyon prize conferred by the Académie des Sciences. In 1856, Le Play founded the Société internationale des études pratiques d'économie sociale (International Society for Practical Studies of Social Economy), which has devoted its energies principally to forwarding social studies on the lines laid down by its founder. The journal of the society, La Réforme Sociale, founded in 1881, is published fortnightly. Emperor Napoleon III, who had met Le Play in Russia during his travels across Europe in the 1840s and held him in high esteem, entrusted him with the organization of the Exhibition of 1855. The following year Napoleon III appointed