At the roots of all our judgments there are a certain number of essential ideas which dominate all our intellectual life; they are what philosophers since Aristotle have called the categories of the understanding: ideas of time, space, class, number, cause, substance, personality, etc. They correspond to the most universal properties of things. They are like the solid frame which encloses all thought; this does not seem to be able to liberate itself from them without destroying itself, for it seems that we cannot think of objects that are not in time and space, which have no number, etc. Other ideas are contingent and unsteady; we can conceive of their being unknown to a man, a society or an epoch; but these others appear to be nearly inseparable from the normal working of the intellect. They are like the framework of the intelligence. Now when primitive religious beliefs...