Byzantine Greek is an old type of Greek that was used as the language of government and most writing under the Byzantine, or Eastern Roman, Empire until the fall of Constantinople to the Turks in 1453. The modern Greek spoken today is different because it is a western dialect of Greek rather than an eastern dialect. The term "Byzantine Greek" is still used today to describe ancient Greek writings that continue to be discovered. These include works by major philosophers such as Aristotle and Plato as well as others such as Euclid and Archimedes. Much information about ancient Greece comes from these writings which are preserved in libraries throughout Europe. In addition to these classical writers, there were many other authors who wrote in Byzantine Greek including Saint John Chrysostom, Pope Clement I, Saint Peter Damian, Saint Boniface, and King Charles V of France. Byzantine Greek died out as a spoken language in the 15th century but not before it had become the official language of Church services and other important matters before the fall of Constantinople. It is still used today by some Christians around the world who have stores of ancient manuscripts and wish to worship God in an ancient Greek manner. There are several differences between modern Greek and Byzantine Greek.