In Beyond Good and Evil, near the end of Chapter 1, Nietzsche wrote:
And yet this hypothesis is far from being the strangest and most painful in this immense and almost new domain of dangerous knowledge, and there are in fact a hundred good reasons why every one should keep away from it who CAN do so!
What was the "almost new domain of dangerous knowledge?"
Was it psychology? If not, what was it?
The text near this quote seems unambiguous enough. This "almost new domain of dangerous knowledge" is Nietzsche's own conception about the Will to power. He acknowledges that the role of this (almost) new factor in human affairs has been revealed to him through psychology but makes (almost rightly) the claim
"nobody had yet harboured the notion the notion of psychology as the Morphology and development-doctrine of the Will to power, as I conceive of it"
The "most strangest and embarrassing hypothesis" in this approach is
[to] regard even the emotions of hatred, envy, covetousness, and imperiousness as life-conditioning emotions, as factors which must be present, fundamentally and essentially, in the general economy of life (which must, therefore, be further developed if life is to be further developed).
The whole passage ends with a full blown panegyric for the discipline
psychology shall once more be recognized as the queen of the sciences, for whose service and equipment the other sciences exist. For psychology is once more the path to the fundamental problems
When he talks about using this dangerous knowledge to sail away from morality, he means morality is just fetters on humans. Psychology, sociology, anthropology, humanities, etc can show us which beliefs/behaviors are fetters. This is dangerous in the sense that it unfetters your neighbor, placing him out of your control and predictive prowess. You don't want anyone to know how to remove these fetters so even their gained perception of these fetters is dangerous. Your gained perception is dangerous for others as well which results in their emotion toward you, who is their now-unknown. You can see examples of this by just looking for one-group's hatred towards another-group's worldview.
However, just because you've unfettered the psychological self through the work of gained perception, does not necessarily mean you've unfettered your physical self. So with your head down you will skulk back to put those fetters back on, at least to make it look like you're fettered to others.
