an empirical theory of ideas free from the burdens imposed alike by sensationalism and apriori ra- tionalism. This accomplishment is, Imake bold to say, one of three or four outstanding feats of intellectual history. For it emancipates us from the supposed need of always harking back to what has already been given, something had by alleged direct or immediate knowledge in the past, for the test of the value of ideas. Adefinition of the nature of ideas in terms of operations to be performed and the test of the validity of the ideas by the consequences of these operations establishes connectivity within concrete experience. At the same time, by emancipation of thinking from the necessity of testing its con- clusions solely by reference to antecedent existence it makes clear the originative possibilities of thinking.