At the same time, folk medicine in the home and village continued uninterrupted, supporting numerous wandering and settled herbalists. Among these were the "wise-women" and "wise men", who prescribed herbal remedies often along with spells, enchantments, divination and advice. One of the most famous women in the herbal tradition was Hildegard of Bingen. A 12th-century Benedictine nun, she wrote a medical text called "Causae et Curae". During this time, herbalism was mainly practiced by women, particularly among Germanic tribes. There were three major sources of information on healing at the time including the Arabian School, Anglo-Saxon leechcraft, and Salerno. A great scholar of the Arabian School was Avicenna, who wrote "The Canon of Medicine" which became the standard medical reference work of the Arab world. ""The Canon of Medicine" is known for its introduction of systematic experimentation and the study of physiology, the discovery of contagious diseases and sexually transmitted diseases, the introduction of quarantine to limit the spread of infectious diseases, the introduction of experimental medicine, clinical trials, and the idea of a syndrome in the diagnosis of specific diseases. ..." The Canon" includes a description of some 760 medicinal plants and the medicine that could be derived from them." With Leechcraft, though bringing to mind part of their treatments, leech was the English term for medical practitioner. Salerno was a famous school in Italy centered around health and medicine. A student of the school was Constantine the African, credited with bringing Arab medicine to Europe. During the Middle Ages, the study of plants began to be based on critical observations. "In the 16th and 17th century an interest in botany revived in Europe and spread to America by way of European conquest and colonization." Philosophers started to act as herbalists and academic professors studied plants with great depth. Herbalists began to explore the use of plants for both medicinal purposes and agricultural uses. Botanists in the Middle Ages were known as herbalists; they collected, grew, dried, stored, and sketched plants. Many became experts in identifying and describing plants according to their morphology and habitats, as well as their usefulness. These books, called herbals included beautiful drawings and paintings of plants as well as their uses. At that time both botany and the art of gardening stressed the utility of plants for man; the popular herbal, described the medical uses of plants. During the Middle Ages, there was an expansion of book culture that spread through the medieval world.