was the simplicity of its doctrine--Islam calls for faith in only One God worthy of worship. Islam also repeatedly instructs human beings to use their powers of intelligence and observation. As Muslim civilization developed, it absorbed the heritage of ancient civilizations like Egypt, Persia and Greece, whose learning was preserved in the libraries and with the scholars of its cities. Some Muslim scholars turned their attention to these centers of learning and sought to acquaint themselves with the knowledge taught and cultivated in them. They, therefore, set about with a concerted effort to translate the philosophical and scientific works available to them, not only from the Greek and Syriac languages (the languages of eastern Christian scholars), but also from Pahlavi, the scholarly language of pre-Islamic Persia, and even from Sanskrit, an ancient Indian language. Most of the important philosophical and scientific works of Aristotle; much of Plato and the Pythagorean school; and the major works of Greek astronomy, mathematics and medicine such as the Almagest of Ptolemy, the Elements of Euclid, and the works of Hippocrates and Galen, were all rendered into Arabic. Furthermore, important works of astronomy, mathematics, and medicine were translated from Pahlavi and Sanskrit. As a result, Arabic became the most important scientific language of the world for many centuries and the depository of much of the wisdom and the sciences of antiquity. The achievement of scholars working in the Islamic tradition went far beyond translation and preservation of ancient learning. These scholars built upon and developed the ancient heritage before passing it on to the West. Muslims excelled in art, architecture, astronomy, geography, history, language, literature, medicine, mathematics, and physics. Many crucial systems such as algebra, the Arabic numerals, and the very concept of the zero (vital to the advancement of mathematics), were formulated ...