The laws of the Cabala were held to explain the functions of the body. The sun rules the heart, the moon the brain, Jupiter the liver, Saturn the spleen, Mercury the lungs, Mars the bile, Venus the kidneys. Gold was a specific against diseases of the heart; the liquor of Luna (solution of silver) cures diseases of the brain. “The remedies,” said Paracelsus, “are subjected to the will of the stars, and directed by them. You ought, therefore, to wait until heaven is favourable before ordering a medicine.” The Paracelsian physicians, for the most part, were a set of dangerous fanatics, who, in their contempt for the principles of Hippocrates, Galen, and Avicenna, and in their reckless use of powerful remedies, many of them metallic poisons, wrought untold misery and mischief. The inevitable reaction set in, and certain of the faculties, particularly that of Paris, prohibited their licentiates, under severe penalties, from using chemical remedies. It is not to be supposed, however, that all iatro-chemists were unscrupulous charlatans. Some of them clearly perceived the significance and true value of the movement which Paracelsus may be credited with having originated. =Andreas Libavius=, or Libau, originally a physician, born in Halle, is best known by his _Alchymia_, published in 1595, which contains an account of the main chemical facts known in his time, and is written in clear and intelligible language, in strong contrast to the mystery and obscurity of his predecessors. He was the discoverer of stannic chloride, still known as the fuming liquor of Libavius, and described a method of preparing oil of vitriol in principle identical with that now made use of on a manufacturing scale. He died in 1616. =John Baptist van Helmont=, a scion of a noble Brabant family, was born in Brussels in 1577. After studying philosophy and theology at the University of Louvain, he directed his attention to medicine, and made himself familiar, in turn, with every system from Hippocrates to Paracelsus. Having spent some time in travel, he settled on his estate at Vilvorde, and occupied himself with laboratory pursuits until his death in 1644.