Memory puts the temporal object in the background by relating to it actively, whereas the perception of time retains the past moment of the object passively and intuitively. Time, Aristotle says, is the numbering number that is itself numbered in the horizon of the before and the after that is inherent in it. The constitutive relation between time and number continues to raise questions for us. The common understanding of time leads us into error, even in its scientific consequences. The term hereditary coordination designates the almost invariable sequence of phenomena culminating in the accomplishment of an instinctive act. Instinct is governed by time, not only because the organism of an animal is subject to well-defined temporal cycles, but because it contains time and temporality within itself. European ethology distinguished itself henceforth by putting the emphasis on the instinct in the most naturalist sense of the term.