Within the realm of
philosopher, opposed to
Assassins Creed, "Nothing is True. Everything is permitted." refers to the nature of reality and our perception of it. "Nothing is true" means that everything we sense and process in our minds is filtered reality, limited by our own bodies. We will never see reality objectively but just through the lens of our eyes, ears, etc. "Everything is permitted" branches off of this first statement; since nothing is true, the mind can generate its own reality. Hence, everything is permitted. This makes more sense in the context of drugs, particularly
psychedelics, that enable the mind to perceive things that are very much disconnected from objective reality.