Lever a place to stand, and I shall move the Earth with it' is a remark of Archimedes who formally stated the correct mathematical principle of levers (quoted by Pappus of Alexandria). It is assumed that in ancient Egypt, constructors used the lever to move and uplift obelisks weighing more than 100 tons. A lever is a beam connected to ground by a hinge, or pivot, called a fulcrum. The ideal lever does not dissipate or store energy, which means there is no friction in the hinge or bending in the beam. In this case, the power into the lever equals
Jan Lever evolutie" (1956; English translation 1958 under the title "Creation and Evolution"). In 1970, Lever was elected member of the Royal Netherlands Academy of Arts and Sciences. In the early 1950s, Lever started research on the neuroendocrine system of the basommatophoran snail, "Lymnaea stagnalis". Lever himself found a particular kind of neurons in the ancylid snail "Ferrissia", and his student Joos Joosse demonstrated those neurons in other snail species. "Lymnaea" became the animal of choice for physiological research at the VU Amsterdam laboratory for decades. At the beginning of his career, Lever’s ideas about evolution and the species concept were inspired