THE earliest biography of Leonardo, that in the book of Antonio Billi, ends with the words: " His spirit was never at rest, his mind was ever devising new things."
They suggest some of the difficulties attendant upon the attempt to write about him.
He was the most versatile genius of the age of the Renaissance, and the more genius approaches the universal, the less can it be seen save in section.
If Leonardo had never either painted or worked in sculpture, his achievements in the more mechanical arts, his inventions, his projects, and the plans he carried out in canalization and engineering, would have received notice more befitting their magnitude.
Were these also taken away from the sum of his activities, his researches in various branches of science, in anatomy, physiology, geology, botany, astronomy, optics, mechanics would still suffice to show to how high a place he is entitled in the history of human culture.
His study of science was in inception a part of the artist's fuller equipment-that he might thereby know the structure of what he represented and the laws of its formation.
It was continued independently of the artistic pun pose and ultimately superseded it. The work in art 01 his later years was either undertaken as illustrating some principle, or as a compromise with necessity, which parted him perforce from the study of natural phenomena and primary causes.
As containing the relation of the two stages self-revealed, his own manuscripts form the best record of his life. They consist of notes of his studies, fragments of letters, personal memoranda, extracts from books, notes of compositions, fragments of treatises, maxims and reflections.
To these I have referred where they directly concern his artistic work or where dated records form landmarks in the chronology.
His life as an artist is a field well trodden. In my state of all-indebtedness to the researches of specialists I can only acknowledge my debt where it is heaviest, viz., to Dr. Richter's " Literary Works of Leonardo da Vinci," to Dr. Muller-Walde's articles in the Jahrbuch, to Professor Uzielli's " Ricerche," to the monograph by Dr. Solmi, and to Mr. Berenson's "Drawings of the Florentine Painters."