That’s a wonderful compendium of graphical proofs. Math Overflow has become such an important mathematical resource: you could imagine this thread being a prett

That’s a wonderful compendium of graphical proofs. Math Overflow has become such an important mathematical resource: you could imagine this thread being a pretty good short book. Graphical reasoning can be transformative, when it’s possible. In the field I worked on as a PhD student, string diagrams are amazingly powerful (http://ncatlab.org/nlab/show/string+diagram http://ncatlab.org/nlab/show/string+diagram). (I introduced the string diagram notation into my dissertation specifically for the sake of one particular proof that would have been incomprehensible expressed any other way.)