This Day in History: , Da Vinci Notebook br Sells for Over $5 Million.br December 12, 1980.br American oil tycoon br Armand Hammer paid br $5,126,000 for the notebook.br At the time, the amount br was the highest ever paid br for a manuscript at auction.br The 72-page manuscript included a number br of drawings and nearly 300 notes written br by Renaissance artist Leonardo da Vinci.br Known as the 'Codex Leicester,' br the notebook was likely written in br 1508. It is one of close to 30 known br notebooks that Da Vinci kept during his life.br Experts believe Da Vinci incorporated br material from the 'Codex Leicester' into br the background of the 'Mona Lisa.'.br Bidding for the manuscript br lasted less than 2 minutes. Hammer br stated, "I expected to pay more.