Giorgio Vasari, Leonardo's first biographer, said that the artist used to sketch "many designs for architecture." In fact, in the so-called "letter of employment" written to Ludovico il Moro in 1482, Leonardo presented himself as a military engineer, able to satisfy the demands of the Duke of Milan in peace and in war, declaring that he "can give perfect satisfaction and to the equal of any other in architecture and the composition of buildings public and private." And then he speaks of his ability in hydraulic engineering for conducting water "from one level to another." Leonardo studied in depth several ancient texts but also the treatises of his own time: in particular the treatise of military and civil architecture by the Sienese engineer and architect Francesco di Giorgio Martini, a text that contains projects for fortifications with bastions, able to offer resistance to the artillery fire. This could explain Leonardo's fascination with fortifications, his involvement in the project to realize the tiburio for the Milan cathedral. He made a great many architectural projects for gardens and elegant buildings, testing out innovative solutions, such as the internal stairs. This allows us to better understand his excellent competence in architecture and why he attempted to plan the "ideal city," conceived as being organized on two different levels, one for pedestrians and the other suitable for vehicle transportation. He also projected also religious buildings, studying different solutions for the centralized plan based on complex systems of architectural symmetries.

As is well known, Leonardo defines painting as the "daughter of nature." His observation of nature, his fascination with every living thing that surrounded him was the main source of his drawings. His entire life was dedicated to investigating and trying to understand the laws of nature. Nature is observed, studied and depicted in all its forms. In fact, Leonardo constantly aims at reproducing every element of nature: animals, flowers, fruits, birds and also, a female smile, the throbbing of the hearth or - following a series of examples - the intricate plait of Renaissance hairdos. All these elements have in common the uninterrupted flow of the secret of life.

Leonardo was an apprentice in Verrocchios workshop, where the young artist was fascinated by the lively and updated environment. Verrocchio taught the practice of drawing to the young Leonardo, who learnt how to describe the world around him with meticulous observation. Moreover, the artist made models in plaster or clay to better understand the world around him in order to reproduce it perfectly. This book wants to trace the career of the artist, passing from the first works by Leonardo with Verrocchio, influenced by the fertile background of Florence at the end of the fifteenth century, to the greater masterpieces. The book also contains a section on the lost works. A train of thoughts connects and explains great frescoes, small paintings and prestigious commissions that have influenced so many artists. Through the pages of the book, a sort of School of the world is traced, revealing the myth of Leonardo.

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.

Leonardo's anatomical studies actually set themselves as an ideal meeting point between artistic and scientific interests because the study of the functioning of the body was essential for artistic practice in order to achieve the correct representation of the human figure. For Leonardo, the artistic practice was determined by an inexhaustible desire for knowledge that led him to study the human body through the Vitruvian proportions and through dissection, carried out by the artist with special care over the middle years of the first decade of the sixteenth century. Drawing becomes essential to understand and reproduce the structure of the male and female body, a "wonderful machine" perfectly thought out. The organs are devices and the body is a machine: Man then becomes a further testing ground for mechanical science.