An assurance, however, of the validity of this supposition is what experience cannot afford us. Grant as much as you please that observation in its ceaseless progress had up to a certain moment only lighted on cases of conformity to the rules which we had inferred from a careful use of earlier perceptions: still the proposition that this accumulation of confirmatory instances, which has so far gone on with out any exception being met with, has increased the probability of a like confirmation in the future, is one that can only be maintained on the strength of a previous tacit admission of the assumption, that the same order which governed the past course of the world will also determine the shape to be taken by its future. This one supposition, accordingly, of there being a universal inner connexion of all reality as such which alone enables us to argue from the structure of any one section of reality to that of the rest, is the foundation of every attempt to arrive at knowledge by means of experience, and is not derivable from experience itself. Whoever casts doubt on the suppo sition, not only loses the prospect of being able to calculate anything future with certainty, but robs himself at the same time of the only basis on which to found the more modest h0pe of being able under definite circumstances to consider the occurrence of one event as more probable than that of another.