The first six books of the elements of Euclid, in which coloured diagrams and symbols are used instead of letters for the greater ease of learners
Oliver Byrne's 1847 edition of Euclid's first six books, printed by Charles Whittingham at the Chiswick Press for William Pickering in London, replaces lettered references in geometric proofs with coloured shapes for students. The 138 diagrams combine red, blue, yellow and black lines, wedges, dotted rules and half-discs into flat primary-colour compositions usable as abstract geometric motifs, borders or chart vocabulary.
