It is not what you believe that makes you insane, but what everyone else does.
I was having a discussion with someone recently who was telling me about a friend of theirs who is a mathematician. This friend, she bragged, saw numbers in everything. Where we saw walls and colors and felt heat or heard trumpets, her friend saw numbers and formulas and complex calculations that described those experiential phenomena. She was so enamored of her friend’s ability to see mathematics in everything that I soon realized her adoration was almost messianic in nature.
Not so very long ago when humans conceived that their reality was populated by spirits and gods – those who heard voices or saw things nobody else did – were thought of as prophets or shaman or some other holy role. Today we call those people schizophrenic or bipolar and pump them full of enough chemicals to keep their visions at bay. Meanwhile people who see numbers that the rest of us do not, or geometry or other empirical modeling tools within nature itself, these folks are called geniuses. They are the new holy folk.
It seems to me that so far as madness goes, that the only difference between a mathematician and a schizophrenic is when and where they were born. In another time somebody who saw numbers and calculations everywhere would have been considered obsessive compulsive and quite likely considered to be hallucinating and dangerous to themselves and others.