Opera mathematica ou oeuvres mathématicques, written by Samuel Marolois together with Hans Vredeman de Vries (1527-1627) in medieval French and printed by Hendricus Hondius between 1614 and 1615, is a systematic introduction to the methods of composition in geometry, perspective, architecture and fortifications. The specimen in the ETH Library is restored by Atelier Strebel AG in 2011, which is recognizable on the obviously older first two parts of the chapter Perspective by the darker color of the pages. The book is fortified with a hard white leather cover (assumed to be sheepskin) and tied together with four purple leather ropes, protecting the thin pages inside which are neatly bound together using section sewing. The entire work is composed of seven-hundred-and-fifty pages divided into six chapters, each followed by a series of illustrations: Gerometrie(47), Perspective(80), Perspective 5 Partie(49), Perspective 6 Partie(24), Les Cincrangs de L’Architecture(26) and Fortification(39). Page 8, 9, 10, 12, 13, 14 till 15, 16, 23, 25, 34, 35, 36, 38, 40 are missing in this specimen and can be found in Fortification (Marolois, 1627). The book measures 297mm high, 420mm long and 70mm wide, therefore, it fits in the book size of Quarto.