Many improvements in agriculture were due to the Arabs. They had a good system of irrigation, practiced rotation of crops, employed fertilizers, and understood how to graft and produce new varieties of plants and fruits. From the Arabs we have received cotton, flax, hemp, buckwheat, rice, sugar cane, and coffee, various vegetables, including asparagus, artichokes, and beans, and such fruits as melons, oranges, lemons, apricots, and plums.
MANUFACTURING
The Arabs excelled in various manufactures. Damascus was famous for its brocades, tapestries, and blades of tempered steel. The Moorish cities in Spain had also their special productions: Cordova, leather; Toledo, armor; and Granada, rich silks. Arab craftsmen taught the Venetians to make crystal and plate glass. The work of Arab potters and weavers was at once the admiration and despair of its imitators in western Europe. The Arabs knew the secrets of dyeing and they made a kind of paper. Their textile fabrics and articles of metal were distinguished for beauty of design and perfection of workmanship. European peoples during the early Middle Ages received the greater part of their manufactured articles of luxury through the Arabs. [24]
COMMERCE
The products of Arab farms and workshops were carried far and wide throughout medieval lands. The Arabs were keen merchants, and Mohammed had expressly encouraged commerce by declaring it agreeable to God. The Arabs traded with India, China, the East Indies (Java and Sumatra), the interior of Africa, Russia, and even with the Baltic lands. Bagdad, which commanded both land and water routes, was the chief center of this commerce, but other cities of western Asia, North Africa, and Spain shared in its advantages. The bazaar, or merchants' quarter, was found in every Moslem city.
GEOGRAPHICAL KNOWLEDGE
The trade of the Arabs, their wide conquests, and their religious pilgrimages to Mecca vastly increased their knowledge of the world. They were the best geographers of the Middle Ages. An Abbasid caliph, the son of Harun-al-Rashid, had the Greek Geography of Ptolemy [25] translated into Arabic and enriched the work with illuminated maps. Arab scholars compiled encyclopedias describing foreign countries and peoples, constructed celestial spheres, and measured closely the arc of the meridian in order to calculate the size of the earth. There is some reason to believe that the mariner's compass was first introduced into Europe by the Arabs. The geographical knowledge of Christian peoples during the Middle Ages owed much, indeed, to their Moslem forerunners.
EDUCATION
Schools and universities flourished in Moslem lands when Christian Europe was still in the "Dark Ages." The largest institution of learning was at Cairo, where the lectures of the professors were attended by thousands of students. Famous universities also existed in Bagdad and Cordova. Moslem scholars especially delighted in the study of philosophy. Arabic translations of Aristotle's [26] writings made the ideas of that great thinker familiar to the students of western Europe, where the knowledge of Greek had all but died out. The Arabs also formed extensive libraries of many thousands of manuscripts, all carefully arranged and catalogued. Their libraries and universities, especially in Spain, were visited by many Christians, who thus became acquainted with Moslem learning and helped to introduce it into Europe.