Leonardo da Vinci's notebook (codex Trivulziano 2162) is a small paper manuscript on which the artist made in the years around 1487 some drawings depicting physiognomy studies, architectural sketches for the Duomo and other buildings in Milan, diagrams of mechanical tools and war machines. Furthermore, on seven pages of the codex one can also see Leonardo's drawings drawn not in ink, but with a metallic point, clearly visible when the page is illuminated with grazing light; in some cases the engraving was then overwritten in ink by another hand, which only followed the original trace in an approximate way. A peculiarity of the Trivulziano codex is the presence of long lists of words, signed by Leonardo, written in his characteristic cursive from right to left. These lists document the artist's attempt to enrich his lexical patrimony by mastering terms derived from Latin, to claim the full scientific dignity of his work and to have more complete access to the writings of humanists and men of science. After the artist's death, the notebook was bequeathed to the pupil Francesco Melzi. At the end of the 16th century, together with other autographs by the master, the manuscript came into the possession of the sculptor Pompeo Leoni. In 1632 it was purchased by Count Galeazzo Arconati, who in 1637 donated it to the Ambrosiana Library, to later take it back in exchange for another Leonardo's autograph, the manuscript D. be part of the rich Trivulzio collection, which in turn merged in 1935 in the collections of the Civic Historical Archives and the Trivulziana Library at the Castello Sforzesco.

This work, belonging to the permanent collection, is open to the public for conservation reasons only on the occasion of temporary exhibitions.