Oliver Byrne published his visually remarkable edition of Euclid’s Elements in 1847. The book is extraordinary: its pages are elaborated with generous four-colour diagrams, illustrations and grids, and each proposition begins with an engraved decorative initial. Its visual similarity to various stylistic themes of the much later Bauhaus and De Stijl movements has been noted, but little attention has been paid to the pedagogical and theoretical insights that shaped Byrne’s choices in illustrating his texts. In this talk, I explain some key philosophical ideas underlying the geometric illustrations and contextualise them amid Byrne’s wider mathematical and empirical preoccupations.