Knowledge, in so far as it is directed to practical matters, has only to enumerate the principal possible attitudes of the thing towards us, as well as our best possible attitude towards it. Therein lies the ordinary function of ready-made concepts, those stations with which we mark out the path of becoming. But to seek to penetrate with them into the inmost nature of things, is to apply to the mobility of the real a method created in order to give stationary points of observation on it.