Beyond Good and Evil by Friedrich Nietzsche Chapter 1 Page 30

But the way is open for new acceptations and refinements of the soul-hypothesis; and such conceptions as “mortal soul,” and “soul of subjective multiplicity,” and “soul as social structure of the instincts and passions,” want henceforth to have legitimate rights in science. In that the NEW psychologist is about to put an end to the superstitions which have hitherto flourished with almost tropical luxuriance around the idea of the soul, he is really, as it were, thrusting himself into a new desert and a new distrust — it is possible that the older psychologists had a merrier and more comfortable time of it; eventually, however, he finds that precisely thereby he is also condemned to INVENT — and, who knows? perhaps to DISCOVER the new.

13. Psychologists should bethink