Quick Answer. Voltaire wrote Candide as a satire of the then-prevalent philosophical optimism advanced by Gottfried Wilhelm Leibniz. Voltaire, moved by contemporary events like the Seven Years' War and the 1755 Lisbon earthquake, felt that optimism was a naive way of viewing the world.
Neurons carry impulses from one place to another, around the many parts of the nervous system. They connect receptors to the central nervous system and also connect one part of the nervous system to another, for example in the brain and spinal cord.
Speed of Impulses. Neurones send messages electrochemically; this means that chemicals (ions) cause an electrical impulse. Neurones and muscle cells are electrically excitable cells, which means that they can transmit electrical nerve impulses. These impulses are due to events in the cell membrane, so to understand the nerve impulse we need to revise some properties of cell membranes.