The Will to Power · Friedrich Wilhelm Nietzsche
567.
The world of appearance, _i.e._ a world regarded in the light of values; ordered, selected according to values--that is to say, in this case, according to the standpoint of utility in regard to the preservation and the increase of power of a certain species of animals. It is _the point of view,_ then, which accounts for the character of "appearance." As if a world could remain over, when the point of view is cancelled! By such means _relativity_ would also be cancelled! Every centre of energy has its _point of view_ of the whole of the _remainder_ of the world--that is to say, its perfectly definite _valuation,_ its mode of action, its mode of resistance. The "world of appearance" is thus reduced to a specific kind of action on the world proceeding from a centre. But there is no other kind of action: and the "world" is only a word for the collective play of these actions. _Reality_ consists precisely in this particular action and reaction of every isolated factor against the whole. There no longer remains a shadow of a _right_ to speak here of "appearance." ... The _specific way of reacting_ is the only way of reacting; we do not know how many kinds and what sort of kinds there are. But there is no "_other,_" no "real," no essential being,--for thus a world _without_ action and reaction would be expressed.... The antithesis: world of appearance and real world, is thus reduced to the antitheses "world" and "nonentity."
Text from Project Gutenberg, public domain in the United States.