We are precluded from questioning Galilei personally about the foundations of Mechanics, or Columbus about the inner feelings of a navigator who discovers new lands, or Sebastian Bach about the merits of Counterpoint, but a great discoverer lives among our contemporaries who is to give us a clue to the nature of discovery. Was it not natural that I should feel the importance of his acceptance of my proposal? Before meeting him again I was overwhelmed with ideas that arose in me at the slightest echo of the word "discovery" in my mind. Nothing, it seemed to me, could be higher: man's position in the sphere of creation and the sum of his knowledge can be deduced from the sum of his discoveries which find their climax in the conceptions civilization and philosophy, just as they are partly conditioned by the philosophy of the time. We might be tempted to ask: which of these two precedes, and which follows? And perhaps the ambiguous nature of this question would furnish us with the key to the answer. For, ultimately, these two elements cannot at all be resolved into the relationship of cause and effect, antecedent and consequent. Neither is primary, and neither secondary: they are intimately interwoven with one another, and are only different aspects of one and the same process. At the root of this process is our axiomatic belief that the world can be comprehended, and the indomitable will of all thinking men, acting as an elementary instinct, to bring the perceptual events in the universe into harmony with the inner processes of thought. This impulse is eternal; it is only the form of these attempts to make the world fully intelligible that alters and is subject to the change of time. This form finds expression in the current philosophy which brings each discovery to fruition, just as philosophy bears in itself constituents of the ripe discovery. It seemed to me that even at this stage of my reflections I was somewhere near interpreting Einstein's intellectual achievement. For his principle of relativity is tantamount to a regulative world-principle that has left a mighty mark in the thought of our times. We have lived to see the death of absolutism; the relativity of the constituents of political power, and their mutability according to view-point and current tendencies, become manifest to us with a clearness unapproached by any experience of earlier historical epochs. The world was far enough advanced in its views for a final achievement of thought which would demolish the absolute also from the mathematico-physical aspect. This is how Einstein's discovery appeared as inevitable.