This diary is the most expensive diary in the world and is valued at more than 30 million dollars. It's amazing how many questions remain unanswered as to why this diary is so expensive and why it was useful to Bill Gates. The diary was kept by Leonardo da Vinci in the XYI century when he lived in Milan, and in his diary, Leonardo da Vinci, the world is like a human organism, a living organism, his body is the earth, his blood is water, streams, and his mind. It is full of drawings, diagrams, mathematical calculations and diagrams explaining why we only see the moon at night, where the rivers come from, and the structure of rocks and minerals. Also, a part of it is written about how he painted the famous work "Mona Lisa", and it is full of writings that are difficult to understand about Sod, a brilliant thinker and his high thinking. Also, the manuscript can only be read in a mirror. You must be asking why Leonardo da Vinci's notes are called "Lester Codex". In 1717, this manuscript was first acquired by Earl Lexter, who named it after himself. Later, an oil magnate bought Hammer and named it Hammer Codex. However, in 1994, Bill Gates, the founder of Microsoft, bought it for 30.8 million dollars, but did not change the name, but in the world's major museums, the manuscript is displayed as an exhibit, and for some reason, the words "Author" are always next to it. A contract is concluded with the condition of placing. It has been displayed in the Seattle Museum since 2003.