The twofold idea "series-structure" crosses a scientific threshold at a certain moment; but it did not start there and it does not stay there, or else crosses over into other sciences, animating, for example, the human sciences, serving in the study of dreams, myths, and organizations. The history of ideas should never be continuous; it should be wary of resemblances, but also of descents or filiations; it should be content to mark the thresholds through which an idea passes, the journeys it takes that change its nature or object. Yet the objective relationships between animals have been applied to certain sub- jective relations between man and animal, from the standpoint of a col- lective imagination or a faculty of social understanding.