Crockett Johnson, *Proof of the Pythagorean Theorem (Euclid)*, 1965, Smithsonian Institution negative number 2008-2519.

Although Crockett Johnson (1906–1975) is best known as the author of the 1955 children’s book *Harold and the Purple Crayon* and had no formal training in mathematics, from the mid-1960s he produced what he called “a series of romantic tributes to the great geometric mathematicians from Pythagoras on up” (Reinhardt Papers, Crockett Johnson Correspondence). At first he relied on diagrams from James Newman’s *The World of Mathematics* as well as other mathematics books, but after a few years he began creating some paintings based on original constructions.

Crockett Johnson, *Squared Circle*, 1968, Smithsonian Institution negative number 2008-2466. This was one of Johnson's own constructions.

Eighty of Crockett Johnson’s paintings are now in the collections of the Smithsonian Institution’s National Museum of American History. They are shown and described at the website http://americanhistory.si.edu/collections/object-groups/mathematical-paintings-of-crockett-johnson.

Ad Reinhardt Papers, 1927–1968. Archives of American Art, Smithsonian Institution. Washington, DC. http://www.aaa.si.edu/collections/ad-reinhardt-papers-5659.