Full Idea
I'm tempted to say that mathematics is so rich that there are indefinitely many ways to prove anything - verbal/symbolic derivations and pictures are just two.
Gist of Idea
There is no limit to how many ways something can be proved in mathematics
Source
James Robert Brown (Philosophy of Mathematics [1999], Ch. 9)
Book Reference
Brown,James Robert: 'Philosophy of Mathematics' [Routledge 2002], p.130
A Reaction
Brown has been defending pictures as a form of proof. I wonder how long his list would be, if we challenged him to give more details? Some people have very low standards of proof.