Codexul Leicester este o colectie de 18 documente duble, adică 36 de file scrise fată-verso de către Leonardo da Vinci între anii 1506 si 1510. Documentele au fost cumparate de Thomas Coke, Duce de Leicester si au apartinut o lunga perioada de timp (1717-1980) urmasilor lui. In 1980 documentele au fost cumparate de miliardarul rosu, americanul Armand Hammer, cel descris in monumentalul film “Reds” (Roşii) si interpretat de Warren Beatty.
Dupa moarte lui Hammer manuscrisul s-a vandut la actualul proprietar, acesta fiind Bill Gates, care a cumpărat Codexul Leicester-Hammer în 1994 cu pretul de 30.8 milioane de USD, codexul devenind astfel cel mai scump document din lume.
Tema principală o reprezintă apa, curentii de apa si aer contiinând studii si desene despre curenti, felul in care se formeaza si se misca. O parte din codex este dedicată astronomiei prin abordarea vizibilitatii si iluminării Pământului si Luni de catre Soare.
Din traducerea engleza
Leonardo was an artist with a consummate understanding of light and shadow, and this is reflected in his science. His observations of the moon in its crescent stage led him to one of the most important scientific statements in the Codex – that sunlight reflected from the Earth’s oceans acts as a secondary light of the moon. This discovery is contrasted with Leonardo’s belief that the moon reflected light because it was covered with water.
The diagram crossing the middle of the page shows the Moon’s surface as having substance and weight. Next to the shaded Moon, at bottom, Leonardo expresses the view that beyond the bright crescent, which is lit by the Sun, the reflection of light from the Earth’s seas gives the rest of the Moon a pale light.
„Some have believed that the moon has some light of its own, but this opinion is false, for they have based it upon that glimmer visible in the middle between the horns of the new moon…this brightness at such a time being derived from our ocean and the other inland seas – for they are at that time illuminated by the sun, which is then on the point of setting, in such a way that the sea then performs the same office for the dark side of the moon as the moon when at the full does for us when the sun is set….” [ Leonardo – Sheet 2A, folio 2r]