Lever Lever A lever ( or ) is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the location of fulcrum, load and effort, the lever is divided into three types. It is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the mechanical advantage
Jan Lever by the Reformational philosophy of philosopher Herman Dooyeweerd. During his student days, Lever became acquainted with the biologist Johann Heinrich Diemer, who had published about Dooyeweerd's approach in the domain of biology in the 1930s. Diemer was a great influence on Lever's thought. Together with Dooyeweerd, Lever wrote four articles about the species concept in the journal "Philosophia Reformata" (1948–1950) in which species were defined as constant types. In his book, "Creatie en Evolutie" (1956), Lever still subscribed to Dooyeweerd’s philosophy but also suggested that it is possible that biological evolution occurred. Later he moved away from these earlier ideas