Hilary Putnam Quote

The physicist who states a law of nature with the aid of a mathematical formula is abstracting a real feature of a real material world, even if he has to speak of numbers, vectors, tensors, state-functions, or whatever to make the abstraction.

in What is Mathematics, in Hilary Putnam (1979). Mathematics, matter, and method. Cambridge University Press. p. 60. ISBN 0521295505.