“The man who, from lack of external enemies and resistances and forcibly confined to the oppressive narrowness and punctiliousness of custom, impatiently lacerated, persecuted, gnawed at, assaulted, and maltreated himself; this animal that rubbed itself raw against the bars of its cage as one tried to “tame” it; this deprived creature, racked with homesickness for the wild, who had to turn himself into an adventure, a torture chamber, an uncertain and dangerous wilderness—this fool, this yearning and desperate prisoner became the inventor of the “bad conscience.”  But thus began the gravest and uncanniest illness, from which humanity has not yet recovered, man’s suffering of man, of himself—the result of a  forcible sundering from his animal past, as it were a leap and plunge into new surroundings and conditions of existence, a declaration of war against the old instincts upon which his strength, joy, and terribleness had rested hitherto. . . .  Let us add at once that, on the other hand, the existence on earth of an animal soul turned against itself, taking sides against itself, was something so new, profound, unheard of, enigmatic, contradictory, and pregnant with a future that thee aspect of the earth was essentially altered”   

“All instincts which do not discharge themselves outwardly turn inward—this is what I call the internalization of man: thus it was that man developed what was later called his ‘soul.’  The entire inner world, originally as thin as if it were stretched between two membranes, expanded and extended itself, acquired depth, breadth, and height, in the same measure as outward discharge was inhibited.”