fictive function to perform; thinking in its lower grades is comparable to paper money, and in its higher forms it is a kind of poetry. Imagination is thus a constitutive part of all thinking. We may make distinctions between practical scientific thinking and disinterested æsthetic thinking. Yet all thinking is finally a comparison. Scientific fictions are parallel with æsthetic fictions. The poet is the type of all thinkers: there is no sharp boundary between the region of poetry and the region of science. Both alike are not ends in themselves, but means to higher ends. Vaihinger’s doctrine of the “as if” is not immune from criticism on more than one side, and it is fairly obvious that, however sound the general principle, particular “fictions” may alter their status, and have even done so since the book was written. Moreover, the doctrine is not always quite congruous with itself. Nor can it be said that Vaihinger ever really answered the question with which he set out. In philosophy, however, it is not the attainment of the goal that matters, it is the things that are met with by the way. And Vaihinger’s philosophy is not only of interest because it presents so clearly and vigorously a prevailing tendency in modern thought. Rightly understood, it supplies a fortifying influence to those who may have seen their cherished spiritual edifice, whatever it may be, fall around them and are tempted to a mood of disillusionment. We make our own world; when we have made it awry, we can remake it, approximately truer, though it cannot be absolutely true, to the facts. It will never be finally made; we are always stretching forth to larger and better fictions which answer more truly to our growing knowledge and experience. Even when we walk, it is only by a series of regulated errors, Vaihinger well points out, a perpetual succession of falls to one side and the other side. Our whole progress through life is of the same nature; all thinking is a regulated error. For we cannot, as Vaihinger insists, choose our errors at random or in accordance with what happens to please us; such fictions are only too likely to turn into deadening dogmas: the old _vis dormitiva_ is the type of them, mere husks that are of no vital use and help us not at all. There are good fictions and bad fictions just as there are good poets and bad poets. It is in the choice and regulation of our errors, in our readiness to accept ever-closer approximations to the unattainable reality, that we think rightly and live rightly. We triumph in so far as we succeed in that regulation. “A lost battle,” Foch, quoting De Maistre, lays down in his “Principes de Guerre,” “is a battle one thinks one has lost”; the battle is won by the fiction that it is won. It is so also in the battle of life, in the whole art of living. Freud regards dreaming as fiction that helps us to sleep; thinking we may regard as fiction that helps us to live. Man lives by imagination.