Leonardo’s drawings of sixty regular polyhedrons are an appendix of the Codex of Ambrosiana, one of the three complete copies of De Divina Proportione by Luca Pacioli.
The drawing situated in Milan is one of the two existing versions: they were destined to Galeazzo Sanseverino whose coat of arms is visible in the first page, after him they were owned by Galeazzo Arconati and donated to Ambrosiana in 1637. The version made for Ludovico il Moro is preserved in Geneva and it is similar to the one in Milan but as good in quality, while the version of Pier Soderini has been lost.
The “divine proportion” to which the title refers is the golden ratio: universal and ancient mathematical formulation according to which any line can be divided into two unequal parts, where the smaller is related to the bigger one, the same identical way in which the bigger relates to the whole. It is considered divine as well as unique, trine and immutable.
In Milan version there are sixty regular polyhedrons, which represent a theory taken from the book XIII of the Elements by Euclid. There is one per sheet, represented in the center of the page and hanging from a sort of identification tag; at the bottom there are captions in Greek while the references between text and drawing are marked by Roman numerals on the outer margin of each sheet. The first object is a sphere, then there is one with twenty-six bases and one with seventy-two (both not regular but useful in architecture). In the end there are the pyramids. The first examples of depictions of regular objects during the Renaissance dates back to Piero della Francesca (Libellus, Trattato d’Abaco, both owned by Luca Pacioli). The Codex of Ambrosiana is a fundamental evidence of Piero’s influence on artistic culture in Milan, thanks to the works of Bramantino, Leonardo and Pacioli.
Not all the critics are favorable to an exclusive attribution to Leonardo; Pacioli, however, mentioned him in numerous documents and the use of perspective, suspension system, the presence of similar documents in the pages of Codex Atlanticus (such as f. 190 a-r, f. 343 v-b) and the rendering of the shadows, that confirm the identity of da Vinci.
AA.VV., Zenale e Leonardo. Tradizione e rinnovamento della pittura lombarda, catalogo della mostra, Milano 1982, p. 168 (con bibliografia precedente);
Pacioli L., De Divina Proportione, introduzione di A. Marinoni, Milano 1982;
De La Mare A.C., Script and manuscripts in Milan under the Sforzas, in Milano nell’età di Ludovico il Moro, Milano 1983, p. 406;
Dalai Emiliani M., Raffaello e i poliedri platonici, in Studi su Raffaello, a cura di M. Sambucco Hamond e M. L. Strocchi, Urbino 1987, pp. 93-109;
Kemp A., Popham A.E., The Drawings of Leonardo da Vinci, London 1994, p.191;
Daly Davis M., Luca Pacioli, Piero della Francesca, Leonardo da Vinci: tra “proportionalità” e“prospettiva” nella Divina proportione, in Piero della Francesca tra arte e scienza, Atti del Convegno internazionale di studi, a cura di M. Dalai Emiliani e V. Curzi, Venezia 1996, pp. 355-362;
Rovetta A., scheda di catalogo in L’Ambrosiana e Leonardo, Novara 1998, pp. 134-139, cat. 58;