The project of a “spiritualist positivism” involved a non-mechanistic biology, and thus Henri Bergson’s development of the spiritualist tradition with his account of duration called for its application to biological life. This chapter shows how Bergson applies his account of genial creation to biological life after having examined his arguments against biological mechanism and finalism, and then his arguments against the expression of both in evolutionary theories. False evolutionism can see in biological development only the addition and association of new elements to old elements, just as false psychology sees in temporal experience only the accumulation of temporal instants. The psychological force throughout life as a whole is what Bergson terms the elan vital, a phrase which he borrowed from an 1899 work on evolution by Andre Lalande. Tendency, understood as the pre-teleological directionality of biological life, belongs to the elan as essentially durational.