mathematics

Philosophy is written in this grand book - I mean universe - which
stands continuously open to our gaze,but which cannot be understood
unless one first learns to comprehend the language in which it is
written. It is written in the language of mathematics, and its
characters are triangles, circles and other geometric figures,
without which it ishumanly impossible to understand a single
word of it; without these, one is wandering about in a dark labyrinth.

Galileo (1623)