If existence were either com- pletely necessary or completely contingent, there would be neither comedy nor tragedy in life, nor need of the will to live. The significance of morals and politics, of the arts both technical and fine, of religion and of science itself as inquiry and discovery, all have their source and meaning in the union in Nature of the settled and the unsettled, the stable and the hazardous. Apart from this union, there are no such things as "ends," either as consummations or as those ends-in-view we call purposes. There is only ablock universe, either something ended and admitting of no change, or else apredestined march of events. There is no such thing as fulfillment where there is no risk of failure, and no defeat where there is no promise of possible achievement. Any philosophy that in its quest for certainty ignores the reality of the uncertain in the ongoing processes of nature denies the conditions out of which it arises. The attempt to include all that is doubtful within the fixed grasp of that which is theoretically certain is committed to insincerity and evasion, and in consequence will have the stigmata of internal contradiction. Every such philosophy is marked at some point by adivision of its subject-matter into the truly real and the merely apparent, asubject and an object, aphysical and a mental, an ideal and an actual, that have nothing to do with one another, save in some mode which is so mysterious as to create an insoluble problem. Action is the means by which aproblematic situation is re- solved. Such is the net outcome of the method of science. There is nothing extraordinary about this conclusion. Interac- tion is auniversal trait of natural existence. "Action" is the name given to one mode of this interaction, namely, that named from the standpoint of an organism.