Leonardo's scientific researches

In addition to Leonardo's immense output as an artist, these years saw him engaged on some of his most arduous scientific and practical labours. To 1505 belongs his MS. on the flight of birds, a subject which he continued to study till his last years. Leonardo was certainly not the first man since antiquity to try to construct machines by which human beings could fly. Roger Bacon says that "an instrument may be made to fly withal if one sit in the midst of the instrument, and do turn an engine, by which the wings, being artificially composed, may beat the air after the manner of a flying bird". Some such inventions are embodied in Leonardo's earliest studies of flight, dating from about 1485, which, like the early machines, show that he had not yet arrived at his experimental approach to every problem. It is characteristic of the growth of his mind that by 1505 he should have gone back to study from nature the principles of flight. He assumed, as all early students of flying assumed, that man would fly in the same way as the birds, and the manuscript consists almost entirely of small studies of birds in flight. Fifteen years ago we should have said that this assumption had been completely falsified by the invention of the propeller-driven aeroplane. But the growth of gliding has shown that Leonardo's approach to the problem may yet prove to be the right one, and recent students of aeronautics are giving more and more attention to the flight of birds. This book is not concerned with Leonardo as an inventor, but his studies of flight have a bearing on his art because they prove the extraordinary quickness of his eye. There is no doubt that the nerves of his eyes and brain, like those of certain famous athletes, were really supernormal, and in consequence he was able to draw and describe movements of a bird which were not seen again until the invention of the slow-motion cinema.

A branch of science more directly related to his painting at this date was anatomy. During his residence at Florence he stayed in the hospital of Santa Maria Nuova and the Anonimo tells us that he was given opportunities of dissection there. Nearly all the drawings in the Anatomical MS. B. date from this period. Many of these are concerned with muscles, especially of the legs and thighs; and in this way they are connected with the drawings for the Battle of Anghiari. They give some justification to the old belief that Leonardo studied anatomy in order to make his representation of the figure more scientific. But, as I have said, Leonardo's scientific researches were undertaken for their own sake, and anatomy was only one manifestation of his curiosity into the workings of nature. It never became to him, as it did to Michelangelo, a means of pictorial expression. In fact, he warns the painter against the abuse of anatomical knowledge: "O anatomical painter" runs a note in MS. E, probably written in Rome about the year 1514, "Beware, lest in the attempt to make your nudes display all their emotions by a too strong indication of bones, sinews and muscles, you become a wooden painter." The reference to Michelangelo, who at that moment was painting the Sistine Ceiling, is unmistakable. Leonardo has understood that the true purpose of Michelangelo's anatomical display is the expression of emotion, but has seen in it the seeds of mannerism. He goes on to write of anatomical knowledge used from a purely naturalistic point of view. Michelangelo might have replied with an exactly analogous criticism of Leonardo's chiaroscuro.

One more of these practical occupations remains to be mentioned, because it led accidentally to Leonardo's greatest commission. I have mentioned that while employed by Cesare Borgia, Leonardo met Machiavelli at Urbino. The two men met again at Imola, and on Leonardo's return to Florence they seem to have become intimate. Each in his own sphere felt the necessity of reconstructing principles on a basis of facts, and brought to the task a great and free intelligence. Machiavelli, moreover, was capable of romantic enthusiasm for unusual abilities; and it was this which made him give all the weight of his position--he was secretary to the republic and friend of the gonfaloniere Soderini--to one of Leonardo's most extravagant schemes. At intervals during his life Leonardo had been concerned with schemes involving the management of water. He had drawn plans of canalisation for the Sforza at Vigevano, Lomellini, Ivrea and in Milan itself. He had attempted to drain the marsh at Piombino, and was later to draw plans for draining the Pontine marshes. Any student of his drawings will remember that the idea of canalisation was always active in his mind. He therefore conceived a plan to end the miserable war between Florence and Pisa which had been dragging on for some years by depriving Pisa of the Arno. Instead the Arno should enter the sea near Stagna and should be navigable as far as Florence. The scheme was first put forward in the summer of 1503 and in August 1504, after a year's discussion, the council decided to adopt it. It is a proof of Leonardo's power of persuasion--fu nel parlare, says the Anonimo, eloquentissimo--that the hard-headed Florentine Signoria was ever won round to a scheme which would extend the resources of modern engineering and must then have been wholly impracticable. Some of Leonardo's maps still remain, and some drawings of men digging; but no trace of the canals. The water refused to flow into the new channels, and in October 1504 the work was abandoned.