A mathematical or logical or any other kind of symbol is invented to serve a purpose purely scientific; it is supposed to have no emotional expressiveness whatever. But when once a particular symbolism has been taken into use and mastered, it reacquires the emotional expressiveness of language proper. Every mathematician knows this. At the same time, the emotions which mathematicians find expressed in their symbols are not emotions in general, they are the peculiar emotions belonging to mathematical thinking.
Apparently from The Principles of Art (1938) by R.G. Collingwood, but I got it from here, and I know nothing else about this.
I hadn’t really thought about this before I saw the quote, but it does seem true that there exist peculiar emotions belonging to mathematical thinking. This has many important consequences.
Mainly though, it makes clear what it is that is hard to communicate when communicating mathematics.