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IT may seem a bold undertaking on the part of one who can claim no acquaintance with the higher mathematics and no familiarity with the experimental work of the physical laboratory, to propose to interpret a principle which is the practical concern only of the mathematician and physicist. It needs no apology, however, for though the principle of relativity has been formu lated by mathematicians and physicists purely as a working principle in mathematics and physics, the particular concepts with which it deals space, time and movement — are metaphysical, and the essential concern of philosophy.
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