"When we say force is the cause of motion we talk metaphysics, and this definition, if we were content with it, would be absolutely sterile. For a definition to be of any use, it must teach us to *measure* force; moreover, that suffices; it is not at all necessary that it teach us what force is *in itself*, nor whether it is the cause or the effect of motion."
- Henri Poincare (1905)
bc, doesn’t know where he found it.
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Hypotheses non fingo - Wikipedia, the free encyclopedia