The first six books of the Elements of Euclid, in which coloured diagrams and symbols are used instead of letters ..
Oliver Byrne's 1847 London edition of Euclid's first six books, published by William Pickering for students of geometry, replaces the usual lettered labels with colour-printed diagrams in red, yellow, blue and black. The plates reduce proofs to flat primary-coloured triangles, wedges, circles and dotted or solid rules set in wide letterpress margins, a source of hard-edged geometric shapes, limited palettes and diagrammatic line notation.
