An idea created by French philosopher Henri Bergson, élan vital is usually translated as "vital force". It is a hypothetical force thought to cause the evolution and development of organisms. The British biologist Julian Huxley remarked that Bergson’s élan vital is no better an explanation of life than is explaining the operation of a railway engine by élan locomotif.

The French philosopher Gilles Deleuze attempted to recoup the novetly of Bergson's idea in his book Bergsonism, though the term itself underwent substantial changes by Deleuze. No longer considered a mystical, elusive force acting on brute matter, as it was in the vitalist debates of the late 19th Century, elan vital in Deleuze's hands denotes a substance in which the distinction between organic and inorganic matter is indiscernible, and the emergence of life undecidable. (Taken from Wikipedia).