History tells us of innumerable retrogressions, of decadences and degenerations. But nothing tells us that there is no possibility of much more basic retrogressions than any so far known, including the most radical of all: the total disappearance of man as man and his silent return to the animal scale, to complete and definitive alteration. The fate of culture, the destiny of man, depends upon our maintaining this dramatic consciousness ever alive in our inmost being, and upon our being well aware, as of a murmuring counterpoint in our entrails, that we can only be sure of insecurity.