This book is one of the many that the present war has brought forth, but it is the fruit of a long gestation. During more than twenty years, while I taught philosophy at Harvard College, I had continual occasion to read and discuss German metaphysics. From the beginning it wore in my eyes a rather questionable shape. Under its obscure and fluctuating tenets I felt something sinister at work something at once hollow and aggressive. It seemed a forced method of speculation, producing more confusion than it found, and calculated chiefly to enable practical materialists to call themselves idealists and rationalists to remain theologians. At the same time the fear that its secret might be eluding me, seeing that by blood and tradition I was perhaps handicapped in the matter, spurred me to great and prolonged efforts to understand what confronted me so bewilderingly. I wished to be as clear and just about it as I could - more clear and just, indeed, than it ever was about itself.