1. For the perpetuation of knowledge. Orders were given to the chief librarian to buy at the king's expense whatever books he could. A body of transcribers was maintained in the Museum, whose duty it was to make correct copies of such works as their owners were not disposed to sell. Any books brought by foreigners into Egypt were taken at once to the Museum, and, when correct copies had been made, the transcript was given to the owner, and the original placed in the library. Often a very large pecuniary indemnity was paid. Thus it is said of Ptolemy Euergetes that, having obtained from Athens the works of Euripides, Sophocles, and Aeschylus, he sent to their owners transcripts, together with about fifteen thousand dollars, as an indemnity. On his return from the Syrian expedition he carried back in triumph all the Egyptian monuments from Ecbatana and Susa, which Cambyses and other invaders had removed from Egypt. These he replaced in their original seats, or added as adornments to his museums. When works were translated as well as transcribed, sums which we should consider as almost incredible were paid, as was the case with the Septuagint translation of the Bible, ordered by Ptolemy Philadelphus. 2. For the increase of knowledge. One of the chief objects of the Museum was that of serving as the home of a body of men who devoted themselves to study, and were lodged and maintained at the king's expense. Occasionally he himself sat at their table. Anecdotes connected with those festive occasions have descended to our times. In the original organization of the Museum the residents were divided into four faculties--literature; mathematics, astronomy, medicine. Minor branches were appropriately classified under one of these general heads; thus natural history was considered to be a branch of medicine. An officer of very great distinction presided over the establishment, and had general charge of its interests. Demetrius Phalareus, perhaps the most learned man of his age, who had been governor of Athens for many years, was the first so appointed. Under him was the librarian, an office sometimes held by men whose names have descended to our times, as Eratosthenes, and Apollonius Rhodius.