This is a collection of notes, letters, and assorted writings of Leonardo da Vinci. There are observations on science, art, theories on how things work, and various subjects, from war, to the future. The Editor gives a explanation of which collections the notes are from. He then translates then, and gives a explanation about the sources of writing. The book was first published in 1906 under the title "Leonardo da Vinci's Notebooks, by Duckworth & Company, it was then updated various times throughout the editor's life, from a 289 page book, to a three volume book, to this later "Definitive Edition".