Deep thinkers, whether of scientific temper of mind or not, have recognized the value of prayer. Vesalius' great contemporary, Michelangelo, who is perhaps the greatest intellectual and artistic genius that the world has ever known--sculptor, architect, painter, poet, and unsurpassed in all these modes of human expression {39} at their highest--was another for whom his crucifix meant much and who frequently turned to it. One of his greatest sonnets is dedicated to the Crucified One. Of Leonardo da Vinci's private life we we know less, but on his death bed he left a sum of money to be used to provide candles to burn before the altar of the little village church at which he had prayed as a boy, so that evidently something of that old fervor of spirit was his at the end. Leonardo da Vinci's mind was one of the most acute in the whole history of mankind. He was a great painter, sculptor, architect, and also a great engineer, a great scientific discoverer, an inventor of all sorts of useful appliances and a veritable marvel of comprehensive appreciation of the significance of even the most obscure things. He is a founder in half a dozen sciences, paleontology, biology, anatomy, physics and mechanics, and nothing makes one feel the smallness of the ordinary man like reading a sketch of Leonardo's achievements. Of course the clergymen scientists have been men of prayer, but few people realize how many of them have made distinguished contributions to the domain of science. Poggendorf's "Biographical Lexicon" contains the names of nearly a thousand clergymen who have made such contributions to science as deserve that their fame should be thus enshrined among the scientists of history. One of the greatest astronomers of the nineteenth century was Father Secchi, a Jesuit, some of whose work was done for a time in America. Among the most distinguished names in modern science are Abbe Breuil and Father Obermaier, who have taught the world so much about the cave man. Both of them are well known for their faithful performance of their religious duties in the midst of their scientific work. {40}