Paul-Henri Thiry, Baron d'Holbach (8 December 1723 – 21 January 1789) was a French-German author, philosopher and encyclopedist. He was an important figure in the French Enlightenment. He was born Paul Heinrich Dietrich in Edesheim, near Landau in the Rhenish Palatinate. He spent most of his life in Paris, where he kept a "salon". He is best known for his atheism. He wrote a lot. Most of his writings are against religion. His best-known book is the "System of Nature".