Excerpts from a lecture by Rudolf Steiner, which took place on 9th October, 1918 in Zurich. Translated into English by D. S. Osmond with the help of Owen Barfield. Taken from https://web.archive.org/save/https://www.francisberger.com/bergers-blog/endorsing-promoting-and-embracing-sexual-perversion-has-become-a-moral-imperative
Certain instinctive knowledge will arise in human nature connected with the mystery of birth and conception, with sexual life as a whole; and this threatens to become baleful if the danger of which I have spoken takes effect.
The effect in the evolution of humanity would be that certain instincts connected with the sexual life would arise in a pernicious form instead of wholesomely, in clear waking consciousness.
These sexual instincts would not be mere aberrations, but would pass over into and configure the social life, would above all prevent men from unfolding brotherhood in any form whatever on the earth, and would rather induce them to rebel against it. This would be a matter of instinct.
So the crucial point lies ahead when either the path to the right can be taken — but that demands wakefulness — or the path to the left, which permits of sleep. But in that case instincts come on the scene — instincts of a fearful kind.
And what do you suppose the scientific experts will say when such instincts come into evidence? They will say that it is a natural and inevitable development in the evolution of humanity. But light cannot be shed on such matters by natural science, for whether men become angels or devils would be equally capable of explanation by scientific reasoning. Science will say the same in both cases: the later is the outcome of the earlier …
Natural science will be totally blind to the event of which I have told you, for if men become half devils through their sexual instincts, science will as a matter of course regard this as a natural necessity. Scientifically, then, the matter is simply not capable of explanation, for whatever happens, everything can be explained by science.
Man would pride himself upon the growth of his instinctive knowledge of certain processes and substances and would experience such satisfaction in obeying certain aberrations of the sexual impulses that he would regard them as evidence of a particularly high development of superhumanity, of freedom from convention, of broad-mindedness!
In a certain respect, ugliness would be beauty and beauty, ugliness.
Yet, nothing of this would be perceived because it would all be regarded as natural necessity. But it would actually denote an aberration from the path which, in the nature of humanity itself, is prescribed for man’s essential being.