It is also uncertain whether their founder was Ptolemy I Soter 20 or his son Ptolemy Philadelphia. ^ Also, the literature states that Demetrius of Phaleron, a peripatetic philosopher and disciple of Theophrastus, and perhaps Aristotle, who began to collect books for library from all over the world during the reign of Ptolemy I Soter, played an important role in the founding of the Library. . The idea of forming a library containing universal works is linked to the expansionist policy of Alexander the Great, which was close to the Ptolemies. Alexander believed that the domination of the world required learning about the thinking and languages of different civilizations through the study of their texts.