I love how Newton could be curt and profound at the same time — his lines about mathematics pop up across his letters and works, and a few of them explicitly talk about calculation, method, or the role of math in science. The most famous I'm always quoting is from a 1675 letter: 'If I have seen further it is by standing on the shoulders of Giants.' It’s not a dry math formula, but it’s directly about cumulative mathematical knowledge and how we build on previous results.
From the 'Philosophiæ Naturalis Principia Mathematica' I often point friends to 'Hypotheses non fingo' — literally 'I feign no hypotheses' — which is his declaration that mathematics-driven deduction, not speculative storytelling, should guide explanation. Then there’s the quip he reportedly said later in life: 'I can calculate the motions of the heavenly bodies, but not the madness of people.' That one foregrounds calculation — the mathematical mastery he had — contrasted with human unpredictability.
Beyond those, he wrote lines like 'Truth is ever to be found in the simplicity, and not in the multiplicity and confusion of things,' which reads like a mathematical aesthetic: prefer simple, elegant principles. When I scan his work I see a mathematician who trusted calculation, geometry, and clear method above rhetorical flourish — and that’s exactly what these quotes capture.