The purpose of knowledge: in this case, as in the case of "good" or "beautiful," the concept must be regarded strictly and narrowly from an anthropocentric and biological standpoint. In order that a particular species may maintain and increase its power, its conception of reality must contain enough which is calculable and constant to allow of its formulating a scheme of conduct. _The utility of preservation_--and _not_ some abstract or theoretical need to eschew deception--stands as the motive force behind the development of the organs of knowledge; ... they evolve in such a way that their observations may suffice for our preservation. In other words, the _measure_ of the desire for knowledge depends upon the extent to which _the Will to Power_ grows in a certain species: a species gets a grasp of a given amount of reality, _in order to master it, in order to enlist that amount in its service._ (c) The Belief in the "Ego." Subject. 481. In opposition to Positivism, which halts at phenomena and says, "These are only _facts_ and nothing more," I would say: No, facts are precisely what is lacking, all that exists consists of _interpretations._ We cannot establish any fact "in itself": it may even be nonsense to desire to do such a thing. "Everything is _subjective,_" ye say: but that in itself is _interpretation._ The subject is nothing given, but something superimposed by fancy, something introduced behind.--Is it necessary to set an interpreter behind the interpretation already to hand? Even that would be fantasy, hypothesis. To the extent to which knowledge has any sense at all, the world is knowable: but it may be interpreted _differently,_ it has not one sense behind it, but hundreds of senses.--"Perspectivity." It is our needs that _interpret the world_; our instincts and their impulses for and against. Every instinct is a sort of thirst for power; each has its point of view, which it would fain impose upon all the other instincts as their norm. 482. Where our ignorance really begins, at that point from which we can see no further, we set a word; for instance, the word "I," the word "do," the word "suffer"--these concepts may be the horizon lines of our knowledge, but they are not "truths." 483. Owing to the phenomenon "thought," the ego is taken for granted; but up to the present everybody believed, like the people, that there was something unconditionally certain in the notion "I think," and that by analogy with our understanding of all other causal reactions this "I" was the given _cause_ of the thinking. However customary and indispensable this fiction may have become now, this fact proves nothing against the imaginary nature of its origin; it might be a life-preserving belief and _still_ be _false._ 484.