Anatomy : the branch of science which played the greatest part in the traditional discipline of the Florentine school

Next to perspective the branch of science which played the greatest part in the traditional discipline of the Florentine school was anatomy. To Castagno it had seemed to offer the basis of scientific realism, to Pollajuolo the mastery of movement. With proportion it lay at the root of Renaissance aesthetics, for if man was the measure of all things, physically perfect man was surely the measure of all beauty, and his proportions must in some way be reducible to mathematical terms and correspond with those abstract perfections, the square, the circle and the golden section. It is not surprising, therefore, that Leonardo studied anatomy with passion throughout his life, and applied his knowledge in painting the great composition of the Battle of Anghiari, and in preparing the lost treatise on the human figure referred to by Pacioli. But quite early his intellectual curiosity led him to investigate aspects of anatomy which could not conceivably benefit his painting. The anatomical drawings in the Windsor MS. B, dated 1489, are studies of skulls, done with a delicacy which makes them works of art, but with scientific intention. This intention is made even clearer in some drawings, done perhaps a year or two later, showing the structure of a bear's foot. Quite recently three drawings by Leonardo have been discovered representing the actual bear. Leonardo had drawn its paws while alive; on its death he dissected it in order to compare them to the human foot. This idea of comparative anatomy appears again in his drawings--he compares the arms of men and monkeys, the legs of men and horses --and is typical of the workings of his mind. It springs from his conception of man as a part of nature, subject to the same laws of growth, controlled by the same chemistry; a conception which transcended his scientific researches, and is one of the roots of his art.

The third branch of the art of painting on which Leonardo insists is proper treatment of the subject. It must be natural, circumstantial and dramatic. He is continually advising the painter to study appropriate gestures and expressions. The student is warned against monotonous attitudes, and in particular against the danger of reproducing his own physical characteristics, a danger more real than might be supposed. Of dramatic impropriety he gives an amusing example: "I recently saw an Annunciation in which the Angel looked as if he wished to chase Our Lady out of his room with movements of such violence that she might have been a hated enemy. And Our Lady seemed as if in despair she was about to throw herself out of the window. Remember not to make such a mistake as this." We may speculate with interest on the author of this picture seen a questi giorni, a probable answer being Botticelli, who in the enthusiasm of his later work was carried beyond classical decorum. This aspect of Leonardo's teaching is easily remembered in front of the Last Supper, and we shall have reason to refer to it again. But we must also keep it in mind when we come to look at those of his compositions in which the treatment of the subject is less obvious, in the St Anne, in the Leda and, above all, in the St John. Strange and perverse as his presentation of these themes may seem, we cannot, with the Trattato before us, dismiss them as merely capricious.

In addition to defining the principal aims of painting, Leonardo gives us practical hints as to how they can be achieved, interesting to us as indications of his own studio practice. He tells the student to avoid above all light which casts a dark shadow, so that even if he is painting in the open air he must do so as if some mist or transparent cloud was between his object and the sun. In sunlight it is better to paint in a courtyard with high walls painted black and a linen curtain stretched over it. The ideal light falls on the object at an angle of 45 degrees. This last shows Leonardo at his most academic, and is a contrast to the Rembrandtesque figure looking out of a dark interior, described above. More sympathetic are his numerous instructions as to how to catch that degree of animation in figures which he valued so highly. "When you are out for a walk," he tells the painter,"see to it that you watch and consider men's postures and actions as they talk, argue, laugh or scuffle together: their own actions, and those of their supporters and onlookers: and make a note of-these with a few strokes in your little book which you must always carry with you. This book should be of tinted paper so that you cannot rub out, but always go on to a new page." He also gives the very sound advice that any student drawing a detail of a figure should first sketch in the figure as a whole, so that the real meaning of the finished part should not be lost sight of. Good examples of his own practice are the studies of the nude at Windsor. These practical hints show how far he was in revolt against the decorative style of the quattrocento. Painters are warned not to surround their figures with dark outlines; rows of frescoes one above the other, the time-honoured Italian way of telling a story in pictures, is blamed on grounds of reason (ragionevolmente biasimato ), and as an alternative Leonardo suggests putting several scenes in the same composition, but cutting them off from one another by "large trees, or angels if they are suitable to the story, or birds or clouds or similar devices ". Scorn is reserved for mere decorators. "There is a certain race of painters", he says, "who from their lack of science have to live by the beauty of blue and gold--vivano sotto la bellezza dell' oro e dell' azzuro. With supreme folly these men allege that they cannot do anything good except at a high cost." I think there can be little doubt that Leonardo was actually thinking of Pintoricchio, who was notoriously extravagant--Consuma, said the papal secretary of him, troppo vino, troppo oro e troppo azzuro. In any case, these maxims foreshadow that great stride in the history of art which the visitor to the Vatican can take by climbing the stairs from Pintoricchio's Borgia apartment to Raphael's Stanze.