Printed document of great historical importance, relating to the donation by Galeazzo Arconati of the Codex Atlanticus and other manuscripts by Leonardo, twelve codices in total, to the Ambrosiana Library. Published for the first time by Uzielli in the second volume of his Research on Leonardo (1884), its importance refers to the first mention of the Atlantic Codex and its attempted purchase by the King of England, rejected by Arconati to proceed with the donation to the Ambrosiana. "In quo non magis commendata fuit Regis magnanimitas in ijs offerendis, [the offering was 3000 gold coins], quam laudatus Arconati animus verè regius, in eisdem repudiandis...volens, ac lubens Ambrosianae Bibliotheca donavit."