Pierre Maupertuis stated in 1746 that many processes in nature are either optimal, or they take extreme values. This is known as the principle of stationary action and is a part of mechanics. It states that physical fields and particles will sometimes take extreme values (which are maximal or minimal). For this reason, it is often called principle of least action. Maupertuis gives a way to determine equations of motion when looking at the action of a mechanical system.