Greek contributions to Islamic world scholarship throughout the Hellenistic world, and Greek mathematics merged with Egyptian and Babylonian mathematics to give rise to a Hellenistic mathematics. The most important centre of learning during this period was Alexandria in Egypt, which attracted scholars from across the Hellenistic world, mostly Greek and Egyptian, but also Jewish, Persian, Phoenician scholars. Most of the mathematical texts written in Greek have been found in Greece, Egypt, Asia Minor, Mesopotamia, and Sicily. Byzantine science was essentially classical science. Therefore, Byzantine science was in every period closely connected with ancient-pagan philosophy, and metaphysics. Despite some opposition to pagan learning, many of the
Ancient Greek phonology and this cluster underwent metathesis early in the Ancient Greek period. Metathesis is likely in this case; clusters of a voiced stop and , like , do not occur in Ancient Greek, since they change to by assimilation (see below), while clusters with the opposite order, like , pronounced , do occur. Ancient grammarians, such as Aristotle in his "Poetics" and Dionysius Thrax in his Art of Grammar, categorized letters () according to what speech sounds ( 'elements') they represented. They called the letters for vowels ('pronounceable', singular ); the letters for the nasals, liquids, and , and the letters