Euclid lived in Alexandria. He was a mathematician and wrote a great work on geometry. No scientific work in the world has lived in quite the same way as has this book of Euclid, for since the time that the Elements of Euclid were written, it was used as a school text book without interruption until a very few years ago. Archimedes was probably the greatest of the Greek scientific thinkers of the third century B.C. He did not live in Alexandria; he was a native of Syracuse in Sicily, but he was in close touch with all the scientific work that was being done there. He was a great scientific investigator, the inventor of many practical and ingenious devices and discovered the principle of moving heavy bodies by means of pulleys and levers. An extraordinarily large ship was made for the King of Syracuse, a ship of marvel to that age. It contained a gymnasium, gardens of most wonderful beauty and full of rich plants, a temple to Aphrodite, a drawing-room with its walls and doors of boxwood, having a bookcase in it, a bath-room with three brazen vessels for {405} holding hot water, and a fish-pond. All the furnishings were of the most exquisite craftsmanship, and all the rooms had floors of mosaic, in which the whole story of the Iliad was depicted in a most marvellous manner. There were doors of ivory, beautiful couches, and it was full of pictures and statues, goblets and vases of every form and shape imaginable. But the ship was so large that no one could move it. Archimedes, however, we are told, launched it by himself with the aid of only a few people. For having prepared a helix (probably some mechanical contrivance with pulleys), he drew this vessel, enormous as it was, down to the sea. And it was said that Archimedes was the first person who ever invented this helix.[1] Archimedes believed it possible to move greater bodies even than the ship, and he is said to have boasted: "Give me a place to stand on, and I will move the earth."