If I have anything of a unity within me, it certainly doesn’t lie in the conscious ‘I’ and in feeling, willing, thinking, but somewhere else: in the sustaining, appropriating, expelling, watchful prudence of my whole organism, of which my conscious self is only a tool. Feeling, willing, thinking everywhere show only outcomes, the causes of which are entirely unknown to me: the way these outcomes succeed one another as if one succeeded out of its predecessor is probably just an illusion: in truth, the causes may be connected to one another in such a way that the final causes give me the impression of being associated, logically or psychologically. I deny that one intellectual or psychological phenomenon is the direct cause of another intellectual or psychological phenomenon – even if this seems to be so. The true world of causes is hidden from us: it is unutterably more complicated. The intellect and the senses are, above all, a simplifying apparatus. Yet our erroneous, miniaturized, logicized world of causes is the one we can live in. We are ‘knowers’ to the extent that we are able to satisfy our needs. Studying the body gives some idea of the unutterable complication. If our intellect did not have some fixed forms, living would be impossible. But that doesn’t prove anything about the truth of all logical facts.
Notebook 34, April-June 1885 paragraph 46