“We have often heard the demand that a science be built on clear and precisely defined basic concepts. In reality, no science, not even the most basic, starts out with such definitions. The true beginnings of scientific activity consist, rather, in the description of phenomena, which are then grouped, classified, and brought into relation with each other. Even when simply describing the material, we cannot avoid applying to it certain abstract ideas, acquired from somewhere or other but certainly not just from the new observations alone.”
—Freud (1915), Drives and their Fates