In a paper presented in 1746 Maupertuis communicated the principle of least action as a general and universal principle. He claimed that it could not only explain the laws of motion but also prove the existence of God. He applied the principle to the study of the collision between elastic and inelastic bodies and to the equilibrium of a lever, finding correct results. In this article we present a detailed analysis of Maupertuis' demonstrations and we show that they had serious problems. His mistakes were criticized by d'Alembert and d'Arcy shortly after the publication of his work.
Pierre-Louis Moreau de Maupertuis; Jean le Rond d'Alembert; principle of least action; history of mechanics
