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 Poincaré, Science and Hypothesis (1905)

Source: https://books.google.com/books?id=5nQSAAAAYAAJ

From Science and Hypothesis, ch. VI: The Classical Mechanics.

Topics: physics