Damn, local LLM just made it up. Thanks for the correction, I should have confirmed before quoting it. Sounded true enough but that's what it's optimized for.. I just searched for the quote and my comment shows up as top result. Sorry for the misinformation, humans of the future! I'll edit the comment to clarify this. (EDIT: I couldn't edit the comment anymore, it's there for posterity.)
---
> Mathematics is an experimental science, and definitions do not come first, but later on.
— Oliver Heaviside
In 'On Operators in Physical Mathematics, part II', Proceedings of the Royal Society of London (15 Jun 1893), 54, 121.
---
Also from Heaviside:
> If it is love that makes the world go round, it is self-induction that makes electromagnetic waves go round the world.
> "There is a time coming when all things shall be found out." I am not so sanguine myself, believing that the well in which Truth is said to reside is really a bottomless pit.
> There is no absolute scale of size in nature, and the small may be as important, or more so than the great.