Bergson alone challenges its theoretic authority in principle.  He alone denies that mere conceptual logic can tell us what is impossible or possible in the world of being or fact; and he does so for reasons which at the same time that they rule logic out from lordship over the whole of life, establish a vast and definite sphere of influence where its sovereignty is indisputable.  Bergson’s own text, felicitous as it is, is too intricate for quotation, so I must use my own inferior words in explaining what I mean by saying this.

In the first place, logic, giving primarily the relations between concepts as such, and the relations between natural facts only secondarily or so far as the facts have been already identified with concepts and defined by them, must of course stand or fall with the conceptual method.  But the conceptual method is a transformation which the flux of life undergoes at our hands in the interests of practice essentially and only subordinately in the interests of theory.  We live forward, we understand backward, said a danish writer; and to understand life by concepts is to arrest its movement, cutting it up into bits as if with scissors, and immobilizing these in our logical herbarium where, comparing them as dried specimens, we can ascertain which of them statically includes or excludes which other.  This treatment supposes life to have already accomplished itself, for the concepts, being so many views taken after the fact, are retrospective and post mortem.  Nevertheless we can draw conclusions from them and project them into the future.  We cannot learn from them how life made itself go, or how it will make itself go; but, on the supposition that its ways of making itself go are unchanging, we can calculate what positions of imagined arrest it will exhibit hereafter under given conditions.  We can compute, for instance, at what point Achilles will be, and where the tortoise will be, at the end of the twentieth minute.  Achilles may then be at a point far ahead; but the full detail of how he will have managed practically to get there our logic never gives us—­we have seen, indeed, that it finds that its results contradict the facts of nature.  The computations which the other sciences make differ in no respect from those of mathematics.  The concepts used are all of them dots through which, by interpolation or extrapolation, curves are drawn, while along the curves other dots are found as consequences.  The latest refinements of logic dispense with the curves altogether, and deal solely with the dots and their correspondences each to each in various series.  The authors of these recent improvements tell us expressly that their aim is to abolish the last vestiges of intuition, videlicet of concrete reality, from the field of reasoning, which then will operate literally on mental dots or bare abstract units of discourse, and on the ways in which they may be strung in naked series.