For many centuries Athens retained her prestige as a centre of art and culture; her schools went on indeed to 529 A.D., that is to say for nearly a thousand years; but the leadership in the intellectual activity of the world passed presently across the Mediterranean to Alexandria, the new trading city that Alexander had founded. Here the Macedonian general Ptolemy had become Pharaoh, with a court that spoke Greek. He had become an intimate of Alexander before he became king, and he was deeply saturated with the ideas of Aristotle. He set himself, with great energy and capacity, to organize knowledge and investigation. He also wrote a history of Alexander’s campaigns which, unhappily, is lost to the world. Alexander had already devoted considerable sums to finance the enquiries of Aristotle, but Ptolemy I was the first person to make a permanent endowment of science. He set up a foundation in Alexandria which was formerly dedicated to the Muses, the Museum of Alexandria. For two or three generations the scientific work done at Alexandria was extraordinarily good. Euclid, Eratosthenes who measured the size of the earth and came within fifty miles of its true diameter, Apollonius who wrote on conic sections, Hipparchus who made the first star map and catalogue, and Hero who devised the first steam engine are among the greater stars of an extraordinary constellation of scientific pioneers. Archimedes came from Syracuse to Alexandria to study, and was a frequent correspondent of the Museum. Herophilus was one of the greatest of Greek anatomists, and is said to have practised vivisection. For a generation or so during the reigns of Ptolemy I and Ptolemy II there was such a blaze of knowledge and discovery at Alexandria as the world was not to see again until the sixteenth century A.D. But it did not continue. There may have been several causes of this decline. Chief among them, the late Professor Mahaffy suggested, was the fact that the Museum was a “royal” college and all its professors and fellows were appointed and paid by Pharaoh. This was all very well when Pharaoh was Ptolemy I, the pupil and friend of Aristotle. But as the dynasty of the Ptolemies went on they became Egyptianized, they fell under the sway of Egyptian priests and Egyptian religious developments, they ceased to follow the work that was done, and their control stifled the spirit of enquiry altogether. The Museum produced little good work after its first century of activity. Ptolemy I not only sought in the most modern spirit to organize the finding of fresh knowledge. He tried also to set up an encyclopædic storehouse of wisdom in the Library of Alexandria. It was not simply a storehouse, it was also a book-copying and book-selling organization. A great army of copyists was set to work perpetually multiplying copies of books.