So, ultimately, in order to understand nature it may be necessary to have a deeper understanding of mathematical relationships. But the real reason is that the subject is enjoyable, and although we humans cut nature up in different ways, and we have different courses in different departments, such compartmentalization is really artificial, and we should take our intellectual pleasures where we find them.
volume I; lecture 22, "Algebra"; section 22-1, "Addition and multiplication"; p. 22-1 - The Feynman Lectures on Physics (1964)