The more one knows of Leonardo's power to paint detail and of his devoted study of nature, the less surprise is there at the traditions with regard to his head of Medusa. It was much for an artist to attempt to make a picture of this hideous head on which were the writhing serpents, the sight of which, according to tradition, turned beholders to stone, but he has succeeded in accomplishing a presentation of the horrible as far as it is possible. The writhing serpents are done with a devotion to detail and a lifelike naturalness that only a great observer of nature could have reached. Besides the serpents in all their varieties there are bats and lizards and vermin of many kinds in the picture, while the cloudy mephitic breath which can be seen issuing from the mouth completes the picture. The intense realism of these details of low animal life is a surprise at that period, but above all a surprise that it should have been done by a man who had such wonderful power of idealization when he wished to use it. It is this combination of qualities so opposite in themselves and often thought mutually exclusive that makes the never-ending surprise of Leonardo's genius. That the painter of the "Last Supper" and the charming "Madonna of the Rocks" should have also made this "Head of Medusa" is indeed difficult to understand, and yet not more than might be expected from one of the greatest of the artists of the Renaissance who is at the same time almost the world's most manifold genius. [Illustration: LEONARDO DA VINCI, MADONNA OF THE ROCKS (LONDON)]