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. Bibliografia essenziale: 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 Rovetta A., scheda di catalogo in L’Ambrosiana e Leonardo, Novara 1998, pp. 134-139, cat. 58;

Leonardo was born in Anchiano in 1452. He was an illegitimate son of notary Ser Piero di Vinci who brought him to Florence in 1469 to give him artistic education.

In 1472 he enrolled to the Compagnia dei Pittori and attended Andrea del Verrocchio’s workshop, participating also in the anatomical research with Antonio and Piero Pollaiolo.

In 1482 Leonardo moved to Milan to serve Ludovico il Moro. He introduced himself as a musician, painter, sculptor, engineer and architect. He painted several works in the court of Moro, among them the Lady with an Ermine and worked on the equestrian monument for Francesco Sforza.

He was a set designer for various court celebrations and studied hydraulic and military engineering. He also devoted himself to physical and natural sciences, as shown in many of his drawings. His most famous work of this period was the Last Supper in Santa Maria delle Grazie (1495 – 1498) where he experimented with tempera on plaster technique instead of the traditional fresco. This resulted in poor state of conservation, which Vasari already mentions in the mid-16^th century.

Ludovico il Moro was defeated by the French in 1500 and Leonardo set off to Venice with his friend, mathematician Luca Pacioli and his student Salai. Then he went to Mantua as a guest of Isabella d’Este and painted her portrait. In the same year he returned to Florence, where he painted Madonna and Child with St. Anne (Louvre, cartoon at the National Gallery of London) and the cartoon for the Battle of Anghiari (1504-1505) for the Salone dei Cinquecento in Palazzo Vecchio.

He was commissioned by the Gonfaloniere of the Florentine Republic, Pier Soderini, who had also commissioned Michelangelo, who was working with the Battle of Cascina. Leonardo experimented with ancient encaustic technique, which turned out to be unsuccessful. Therefore, the project was not completed and today only some drawings have remained of the lost cartoon, such as the Tavola Doria.

Leonardo traveled to Urbino, Pesaro, Rimini and Cesenatico where he continued to study hydraulics, cartography and fortifications, but in 1505 he returned to Milan. He made several trips between Lombardy, Florence and Rome and continued his science research, but he was never commissioned by the Vatican, which favored the works of Raphael and Michelangelo.

Disappointed Leonardo left Italy in 1517 to take refuge in the castle of Cloux, near Ambroise in France, under the protection of Francis I, who gave him an annual pension. He brought numerous paintings with him, like Mona Lisa, which he painted in Florence in 1503. In France he continued his anatomical and scientific studies of which he left many drawings.

Leonardo died in 1519.

Pinacoteca Ambrosiana was established in 1618 by cardinal Federico Borromeo, when he donated his art collection to the Ambrosiana library, which was founded by him as well in 1607. The building was named after the patron saint of Milan, St. Ambrose.

It was the first museum in the world to be open to the public. The history of the Pinacoteca and the library goes hand in hand, as this was also the first library to be open to the public. The book collection includes prestigious volumes, among them Petrarch’s Virgil with illuminated manuscript by Simone Martini and Da Vinci’s Codex Atlanticus, donated in 1637 by Galeazzo Arconati.

In fact, cardinal’s plan was to display art with its symbology and evocative power to serve Christian values reaffirmed by the Council of Trent (1545-1563), which were threatened by the diffusion of the Protestant reformation.

The academy was added in 1637 and transferred to Brera in 1776. It was supposed to be an artistic school of painting, sculpture and architecture which would allow the students to learn from the great models of the history.

The building was designed by architect Fabio Mangone (1587-1629) and it is located in the city center. The space is expanded over 1500 square meters and divided into twenty-two rooms. The cardinal illustrated the works and the objects himself in his book in Latin, Museum (1625), which still today represents the main nucleus of the Pinacoteca.

Through commissions and purchases Federico Borromeo’s collection grew with the paintings of Lombard and Tuscan schools, among them works by Raphael, Correggio and Bernardino Luini and casts from Leone Leoni’s workshop, arriving to a total of 3000 artworks of which 300 are exhibited.

There are great masterpieces such as the Portrait of a Musician by Leonardo Da Vinci (1480), Madonna del Padiglione by Botticelli (1495), the cartoon for the School of Athens by Raphael (before 1510), the Holy Family with St. Anne and Young St. John by Bernardino Luini (1530) and the Rest on the Flight into Egypt by Jacopo Bassano (1547).

A great part of the collection is dedicated to landscape and to still life, because the Cardinal saw the nature as an important tool raising the human mind into the Divine. For this reason, Federico collected Caravaggio’s Basket of Fruit and the miniature paintings by Jan Brueghel and Paul Brill.

After the cardinal’s death the collection was enriched with the donations of the artworks from 15th and 16th centuries, such as the frescoes by Bramantino and Antonio Canova and Bertel Thorvaldsen’s marble self-portraits. Museo Settala, one of the first museums in Italy, founded by canonical Manfredo Settala (1600-1680), was joined to Pinacoteca Ambrosiana in 1751. The museum is a sort of science history museum with a variety of curiosities of all time.

During the period of growth, the museum required some structural and architectural changes as well, including the expansion of the exhibition halls between 1928 and 1931, which were decorated with 13th century miniature motifs of Ambrosian codes, and between 1932 and 1938 a new series of restorations was implemented under the guidance of Ambrogio Annoni. The renowned readjustment in 1963 was curated by architect Luigi Caccia Dominioni and the museum excursus was concluded with the current reorganization between 1990 and 1997.