There can be little doubt, I think, that the quality and texture of recent scientific and philosophical thought mark a greater break with the past than any innovations such as were introduced by a Gallileo or a Newton, a Descartes or a Kant. The switch over from the logicality and essential rationality of these men to the irrationalisms, the anti-intellectualisms, and the new logics of the moderns, is not at all on the same footing as that deepening of our concepts of knowledge and reality which we associate with the masters of thought, more particularly with the critical philosophy of Kant. Strong and significant as these earlier changes were, they marked but the onward strides of an art of thinking which remained in its essence the same in spite of them. But the thinkers in the public eye to-day are exploring in unknown regions, and it may turn out that they have got beyond their depth. Whatever their fate, it seems undeniable that the experiments that they have made and are making constitute, at points at least, and for the time being, a veritable revolution.