Arguably the greatest, alongside Euler, of eighteenth-century mathematicians. Although he was born in Turin and spent the early part of his life there, he eventually settled in Paris and is normally deemed to be French. Much of his important work was done in Berlin, where he was Euler's successor at the Academy. His work, in common with that of most important mathematicians of the time, covers the whole range of mathematics. He is known for results in number theory and algebra but is probably best remembered as a leading figure in the development of theoretical mechanics. His work Mécanique analytique, published in 1788, is a comprehensive account of the subject. In particular, he was mainly responsible for the methods of the calculus of variations and the consequent Lagrangian method in mechanics.