That tolerance and curiosity ushered in a golden age of Islamic learning centered in Baghdad. The Abbasids oversaw an effervescence of culture unlike anything that had been seen since Hellenistic times. Arabic replaced Greek not only as the language of commerce and religion, but also of culture. Philosophy, medicine, and poetry were all written in Arabic, although Persian remained an important literary language. And Baghdad became the world's center of scholarship, with its house of wisdom and immense library. Muslim scholars translated the works of Greek philosophers, including Aristotle and Plato, as well as scientific works by Hippocrates, Archimedes, and especially the physician Galen. And they translated and preserved Buddhist and Hindu manuscripts that might otherwise have been lost.