Section 1
Mathematics, Geometry and Art

C. A. Folio 709 recto
Study in Perspective

pen and ink, with finishing touches in watercolor, circa 1513-16 (?)
©Veneranda Biblioteca Ambrosiana/Mondadori Portfolio

Folio 709 recto
Verserio (Catalogue 4, p. 146) believes that this drawing, of an unusual geometric shape, to be a copy done by one of Leonardo's students. He bases his assessment on the technical and stylistic weakness of the architectural elements on the back (or verso) of this same sheet. This drawing shares many of the elements of Leonardo’s drawings for Pacioli’s De divina proportione (1509), as in the icosidodecahedron on C. A. folio 707 recto; however, this cubic planar construction does not belong to that treatise. The form, consisting of three intersecting quadrilateral planes, is not a regular geometric or Platonic solid. As in the Pacioli illustrations, this drawing presents a skeletal, or transparent version, allowing one to see through to the other planes.

C. A. folio 707 recto
Platonic Icosidodecahedron (transparent)

pen and ink with traces of pin-pricks, circa 1498 (?)
©Veneranda Biblioteca Ambrosiana/Mondadori Portfolio