If, in the course of time, commonplace and impersonal ideas are automatically reinforced while unusual ideas fade away, so that almost everyone, with a mechanical certainty, is bound to become increasingly mediocre, this explains why, despite the thousandfold possibilities available to everyone, the average human being is in fact average. And it also explains why even among those privileged persons who make a place for themselves and achieve recognition there will be found a certain mixture of about 51 percent depth and 49 percent shallowness.