It has recently been argued by a learned and acute investigator of economic origins that "invention is the mother of necessity," and not the child.[45] Such a complete reversal of all our ordinary thought about the matter seems at first sheer paradox. What, one may ask, can ever suggest an invention and what can give it welcome and currency but an existing need--which, if it happens to be for the time being latent and unconscious, needs only the presentation of its appropriate means of satisfaction to "arouse" and "awaken" it fully into action? But this paradox as to invention is at all events not more paradoxical than the view as to the reception of new commodities and the rise of new desires that has been above suggested. What it appears to imply is in principle identical with what has seemed, from our consideration of the other aspect of the general situation, to be the simple empirical fact; neither the existence of the new commodity nor our interest in it when it is presented admits of explanation as an effect on each particular occasion of a preexisting unsatisfied desire for it. What both sides of the problem bring to view is a certain original bent or constitutive character of human nature--a predisposition, an _elan vital_ perhaps, which we must recognize as nothing less than perfectly general and comprehensive--finding expression in inventive effort and likewise in the readiness with which the individual meets a new commodity halfway and gives it opportunity to become for him, if it can, a new necessity and the source of a new type of satisfaction.