Errett Bishop is known for his principled opposition to the law of excluded middle. His opposition was so principled in fact that he viewed it (or more precisely the classical mathematician relying upon it) as The Devil, and composed the following verse to bring the point home:
The devil is very neat. It is his pride \ To keep his house in order. Every bit \ Of trivia has its place. He takes great pains \ To see that nothing ever does not fit. \ And yet his guests are queasy. All their food, \ Served with a flair and pleasant to the eye, \ Goes through like sawdust. Pity the perfect host! \ The devil thinks and thinks and he cannot cry.
This is on page 14 in Bishop, E. Schizophrenia in contemporary mathematics. Errett Bishop: reflections on him and his research (San Diego, Calif., 1983), 1--32, Contemp. Math., 39, American Mathematical Society, Providence, RI, 1985.