Hence sexual love was anathema to them: and even marriage, grudgingly conceded but rarely accepted, was an object of horrified scorn. In consequence, it was not surprising that sexual interests and activities should go underground, as it were, and that amatory aids and encouragements likewise developed their secretive hiding places, their esoteric emporia, their identifiable but undisclosed havens. The result was that, as the Middle Ages advanced, two basic views appeared to come into force. Laws that governed the marriage ceremonial and its consequent domestic involvements and possessive obligations. And laws that related to love as such, to the _amor naturalis_, as defined by St. Thomas Aquinas, both in its romantic sense as a kind of amatory but undefined ideal, and in its sexual implications that reached as far as adultery, under certain subdued, well-controlled, and unpublicized circumstances. All these occasions created a hungry, frantic demand for philtres and phials and nostrums of all varieties, of all degrees of efficacy. They bloomed upon the markets, and gave employment and a vast impetus to quacks and adventurers, to alchemists and beldams, in furnishing the tantalizing apparatus of love. * * * * * One of the most dominant humanists during the Middle Ages was Albertus Magnus (1193–1280). Of Germanic birth, he was educated in Padua and Bologna. On account of his encyclopedic knowledge, he was generally known as the Doctor Universalis. Professor of theology, scientist, teacher, he achieved, both by his voluminous writings and his lectures, an almost legendary reputation. In one of his treatises, _De Secretis Mulierum_, he expounds on feminine matters and then proceeds to discuss, in his _De Virtutibus Lapidum Quorundam Libellus_, the virtues and properties of certain precious and semi-precious stones. In an amatory direction, Albertus Magnus gives suggestions, as if they were prescriptive and categorically assertive, on how to win the favor and affection of a person: Take the stone called Chalcedony. It may be black or red, and is extracted from the stomach of swallows. Wrap the red stone in a linen cloth or in calf skin and place it under the left armpit. Although the philtre that is intended to inspire erotic excitations is normally a drink, a fluid, Albertus Magnus’ recipe is virtually and in its ultimate sense a potion. He adds, on a later occasion in the same text: If you want to promote love between two people, take the stone called Echites, by some termed Aquileus—because eagles place it in their nests. It is purple in color and is found on the sea shore: sometimes, too, in Persia. And it always contains within itself another stone that makes a sound when moved. The ancient philosophers say that this stone, worn suspended on the left arm, effects love between a man and a woman.