The term engineering comes from the Latin word ingenium that means talent, gift. Thus, according to this definition, the engineer was an intelligent, practical man, able to solve problems. Who better than Leonardo could fit this description perfectly? Leonardo studied in depth ancient texts and the treatises written by the most innovative Florentine and Sienese engineers of that time. Among them, one of the most important was Brunelleschi who was considered the repository of Renaissance knowledge. In the letter of employment written to Ludovico il Moro in 1482, Leonardo presented himself as an architect and as a skilled military and hydraulic engineer, adding only at the end his ability in sculpture and painting. Leonardo diffused these innovations, improving them thanks to his genius. The artist studied engineering in more than thousand folios, now kept in the Codex Atlanticus and in the first of the Madrid manuscripts.