Mathematics has given science a direct way to express some of their laws and relations, but it has also exerted a deep influence indirectly, as a source of associations, analogies and metaphors, i.e., it offers some ways to indicate, intuitively things that can not, or should not, be said. After some general points regarding this problem, a small part of an epic written by the author about the end of the Aztec empire is analyzed as a metaphor where a branch of mathematics, chaos theory, plays a fundamental role.