Glossary · Manuscripts
Folio
A single leaf within a bound manuscript or codex — the basic unit of scholarly citation for Leonardo's notebooks. Each folio has a front (recto) and a back (verso), abbreviated r and v in citations.
Definition
A folio (from Latin folium, "leaf") is a single physical leaf — a sheet of paper or parchment — within a bound manuscript. Each folio has two sides: the recto (the front, which faces you when the book is open to the right-hand page) and the verso (the back, the left-hand page when opened).
In scholarly citations of Leonardo's notebooks, folios are numbered sequentially within each codex, and recto/verso is indicated by r or v. For example, "Codex Atlanticus, 270v" means the back side of folio 270 in the Codex Atlanticus.
How Leonardo's Notebooks Are Organised
Leonardo's surviving manuscripts contain approximately 6,000 pages (c. 3,000 folios) across some 20 major codices and collections. After his death, many loose sheets were bound by Francesco Melzi and later collectors — meaning the folio numbers do not always reflect Leonardo's own working order. The Codex Atlanticus alone contains 1,119 folios, assembled from individual sheets of varying sizes.