In most of the histories of philosophy that I know, philosophic systems are presented to us as if growing out of one another spontaneously, and their authors, the philosophers, appear only as mere pretexts. The inner biography of the philosophers, of the men who philosophized, occupies a secondary place. And yet it is precisely this inner biography that explains for us most things. … Philosophy answers to our need of forming a complete and unitary conception of the world and of life, and as a result of this conception, a feeling which gives birth to an inward attitude and even to outward action. But the fact is that this feeling, instead of being a consequence of this conception, is the cause of it. Our philosophy — that is, our mode of understanding or not understanding the world and life — springs from our feeling towards life itself. And life, like everything affective, has roots in subconscious, perhaps in unconsciousness. ¶ It is not usually our ideas that make us optimists or pessimists, but it is our optimism or our pessimism, of physiological or perhaps pathological origin, as much the one as the other, that makes our ideas. ¶ Man is said to be a reasoning animal. I do not know why he has not been defined as an affective or feeling animal. Perhaps that which differentiates him from other animals is feeling rather than reason. More often I have seen a cat reason than laugh or weep. Perhaps it weeps or laughs inwardly — but then perhaps, also inwardly, the crab resolves equations of the second degree. ¶ And thus, in a philosopher, what must needs most concern us is the man.