Among her correspondents were people of the humble walks of life as well as the highest representatives of Church and State. There were simple monks and noble abbots; dukes, kings and queens; archbishops and cardinals and no fewer than four Popes. Letters came to her from the orient and the occident, from the patriarch of Jerusalem, from Queen Bertha of Greece, from Frederick Barbarossa, Philip the Count of Flanders, St. Bernard, the professors of the University of Paris; from Henry II of England, and from his grand-daughter Eleonora, "The Damsel of Brittany." It is safe to say that no woman during the Middle Ages exercised a wider or more beneficent influence than did this humble Benedictine abbess of Bingen on the Rhine and had unsought so large a number of distinguished correspondents. And, if we accept the criterion that influence is measured by the number and nature of one's relations, it would be difficult to find in any age relations that were more select or more cosmopolitan. But her astonishing collection of letters is the slightest product of her intellectual activity. She is without doubt the most voluminous woman writer of the Middle Ages. Her works on theology, Scripture and science make no less than six or eight large octavo volumes. The Bollandists, than whom there is no more competent authority, express their amazement at the amount and quality of Hildegard's work. Witness the following language of one of their number: "Although we may not be surprised that our saint was interrogated regarding secret things by so many men eminent both by reason of their dignity and their learning, I am nevertheless forced to recognize with stupefaction that a woman without instruction, and who had not acquired knowledge by study, was consulted concerning the most difficult questions of theology and the most subtle of Holy Scriptures, and that she gave, without hesitation, the answers that were demanded by theology and Scripture."[42] Is it, then, surprising that the famous William of Auxerre, after a critical examination of her works, should compare her with Peter Lombard, the celebrated "Master of the Sentences,"[43] and one of the most learned of the Schoolmen, and write that Hildegard is _Sententiarum Magistra_--Mistress of the Sentences--and that "in her works the words are not human but divine"? Has any woman writer ever received higher praise, and from one so competent to express an opinion as the scholarly divine of Auxerre? Herrad, the gifted abbess of Hohenburg in Alsace, was a contemporary of Hildegard, and, like her, was noted for her culture and wide range of knowledge. She is chiefly known for her _Hortus Deliciarum_, a remarkable work, encyclopaedic in character, which she wrote for the nuns of her convent and which was designed to embody in words and in pictures the knowledge of her age.