The Codex Madrid I is Leonardo's main work on technology. For a long time, it was lost, and its rediscovery in 1965 in Madrid was considered a sensation. It provides a new image of Leonardo as an engineer. The Codex consists of two parts, one with refined machine drawings and the other with theoretical considerations. Leonardo observes the state of technology in his time and aims to improve it. He analyzes, notes, and develops - for example, a modern freewheel, gears in involute form, textile machines, clocks, locks in all details, reduced friction, and improved bearings. His contributions to dynamics, statics, and hydraulics point far into the future. However, the first edition from 1974 left some questions and wishes unanswered. The four-volume edition presented here, developed at RWTH Aachen, now offers a completely re-conceived edition: Volume 1 and 2 contain the...