This is art historian Clark’s excellent study of Leonardo. Among his many books also is Civilization, which was subsequently turned into an excellent television series.
A few points of especial consequence.
In discussing the painting of the Virgin and St Anne, Clark writes
Finally, [Leonardo] arrives at the solution which we know in the Paris picture. By considerable distortion he has achieved a perfect balance throughout. The design has the exhilarating quality of an elaborate fugue: like a masterpiece of Bach it is inexhaustible. We are always discovering new felicities of movement and harmony, growing more and more intricate, yet subordinate to the whole; and, as with Bach, this is not only an intellectual performance; it is charged with human feeling.
Elsewhere in his book, Clark discusses the integrity of Mozart and the inevitability of his music, and links these characteristics to the work of Leonardo. Nowhere in his book does Clark rate any other composer as highly as Bach and Mozart.
It is worth digressing to notice the differences in pen technique…. The whole system of shading has changed. Instead of diagonals the lines of shading are directed to indicate depth. Thus, a shadow on a cylinder, instead of being made up of graded diagonals, will consist of lines drawn at right angles to the side of the cylinder, following the form. It is essentially a sculptural style, rejecting the data of sight in favour of a convention based on knowledge…. On the whole, this linear convention was little used by Italian painters. It is a northern, in particular a German style, and we cannot reject the possibility that Leonardo was influenced by the prints and drawings of Dürer, which much impressed Italian artists of that date…. This is what Cézanne meant when he praised a picture by saying that it was dessiné dans la forme.
In his culminating chapter Clark returns to the oppositional interrelationship between Dürer and Leonardo, specifically between Leonardo’s prophetic obsession with the deluge and Dürer’s depiction of a dreamt deluge that also drowns the whole land. I myself have been acquainted for some time with both of these depictions, and I incline strongly to Leonardo’s observation rather than to Dürer’s dream, which, however, is equally valid intellectually, although it is Leonardo’s that I use in my own work.