The book is arranged in four main sections. The first consists of extracts from the famous Italian art-historian, Vasari's almost contemporary life of Leonardo, translated into Swedish and freely commented upon and greatly expanded by Dr. Sirén. Many illustrations are given showing Leonardo's extraordinary knowledge of mechanics, engineering, architecture, fortification, anatomy, etc. Dr. Sirén finally demolishes one of our pet illusions, i. e., that Leonardo died in the arms of Francis I of France, by showing that King Francis was at St. Germain-en-Laye, attending the birth of a son, at the moment when Leonardo was breathing his last at Cloux in Touraine. It appears this was one of Vasari's occasional "decorations of the truth" for the sake of picturesqueness. Another myth was that Leonardo prostrated himself at the feet of the church at his last hour with tears and cries of repentance for the independence of thought for which he had consistently stood. In this connexion it is noteworthy that he studiously avoided introducing halos or nimbuses round the figures in his religious pictures! Neither is there more than one example of the cross in any of his undoubted works, and that may have been added by another hand afterwards. His object was plainly to accentuate the simple human and natural side in everything that he touched. Even the head of the Christ in _The Last Supper_ has no radiance; the Teacher is painted just as he might have been seen by ordinary vision. The distinction of Leonardo's sacred figures depends upon the superior beauty and majesty of expression and bearing. This was a very daring innovation on Leonardo's part. The second portion of Dr. Sirén's learned volume treats of Leonardo's pictures and sculptures in more detail; his scientific work is sufficiently dealt with in the earlier part of the volume, for after all, his fame depends mainly upon his standing as an artist. Special chapters are devoted, respectively, to the work of his youth: _The Adoration of the Magi_, the _Madonna among the Rocks_, _The Last Supper_, _The Battle of the Standard_, _Leda and the Swan_, _John the Baptist_, _St. Anne_, and his studies for equestrian statues, etc. Dr. Sirén strongly accentuates the fact that Leonardo's leading motive was Movement. While he rivaled Michel Angelo in form, Titian and Giorgione in color, and Raphael in composition, his greatest efforts were concentrated upon the true rendering of life and action. His brilliant effects of light and shade, for which he was particularly noted, were skilfully used to emphasize the impression of vital energy which he felt to be the principal object of the true painter's art.