This chapter focuses exclusively on medieval Jewish civilization, from the fall of the Roman Empire to about 1492. It includes alphabetically organized entries, written by scholars from around the world, include biographies, countries, events, social history, and religious concepts. Jewish interest in science was both "theoretical" and "practical", to employ the standard Greek (-Arabic) terminology. From a theoretical perspective, all knowledge was viewed as of divine origin, and even prior to the teaching of Maimonides and other philosophers that a knowledge of science and of the workings of the universe is necessary in order to comprehend the true nature of God, Jews must have been intrigued by physical and natural phenomena. Certainly one of the most important scientists of the era, and of the entire medieval period, was the aforementioned Abraham bar Hayya of Barcelona. In Provence in the thirteenth century important translation from Arabic into Hebrew continued, particularly with the renowned Ibn Tibbon family.