"Appearance" is an adjusted and simplified world, in which our _practical_ instincts have worked: for us it is perfectly true: for we _live_ in it, we can live in it: _this is the proof_ of its truth as far as we are concerned.... The world, apart from the fact that we have to live in it--the world, which we have _not_ adjusted to our being, our logic, and our psychological prejudices--does _not_ exist as a world "in-itself"; it is essentially a world of relations: under certain circumstances it has a _different aspect_ from every different point at which it is seen: it presses against every point, and every point resists it--and these collective relations are in every case _incongruent._ The _measure of power_ determines what _being_ possesses the other measure of power: under what form, force, or constraint, it acts or resists. Our particular case is interesting enough: we have created a conception in order to be able to live in a world, in order to perceive just enough to enable us to _endure_ life in that world.... 569. The nature of our psychological vision is determined by the fact-- (1) That _communication_ is necessary, and that for communication to be possible something must be stable, simplified, and capable of being stated precisely (above all, in the so-called _identical_ case). In order that it may be communicable, it must be felt as something _adjusted,_ as "_recognisable_." The material of the senses, arranged by the understanding, reduced to coarse leading features, made similar to other things, and classified with its like. Thus: the indefiniteness and the chaos of sense-impressions are, as it were, _made logical._ (2) The _phenomenal_ world is the adjusted world which _we believe to be real,_ Its "reality" lies in the constant return of similar, familiar, and related things, in their _rationalised character,_ and in the belief that we are here able to reckon and determine. (3) The opposite of this phenomenal world is not "the real world," but the amorphous and unadjustable world consisting of the chaos of sensations--that is to say, _another kind_ of phenomenal; world, a world which to us is "unknowable."