COVENT-GARDEN, _April 20, 1666_. At my Lady Verney's, the place of my residence. While Greatrakes acquired great celebrity on account of the numerous cures which he performed, he was unable to explain the nature of his healing powers. In a letter to the Hon. Robert Boyle, he expressed the belief that many of the pains which afflict men, are of the nature of evil spirits. "Such pains," wrote he, "cannot endure my hand, nay, not my glove, but flye immediately, though six or eight coats and cloaks be put between the parties' body and my hand, as at York House, the Lady Ranalough's and divers other places, since I came to London." VAN HELMONT JOHANN BAPTIST VAN HELMONT, a celebrated Belgian physician, scholar and visionary, of noble family, was born at Brussels in 1577. At an early age he began the study of medicine, and was appointed Professor of Surgery at the University of Louvain. Becoming, however, infected with the delusions of alchemy, and being possessed of an ardent imagination, he inclined naturally to the study of occult science, and was infatuated with the idea of discovering a universal remedy. He was, moreover, a follower of the eminent theologian, Johann Tauler (1290-1361), founder of mystic theology in Germany. Van Helmont has been described as an enthusiastic and fantastic, though upright friend of the truth. He adhered to the theosophic and alchemistic doctrines of a somewhat earlier epoch, and was an admirer of the dogmatic pseudo-philosophy of Paracelsus. The German writer, Johann Christian Ferdinand Hoefer (1811-1878), said that Van Helmont was much superior to Paracelsus, whom he took as his model. He had the permanent distinction of revealing scientifically the existence of invisible, impalpable substances, namely gases. And he was the first to employ the word gas as the name of all elastic fluids except common air.[260:1] Van Helmont graduated as Doctor of Medicine in 1599, and after several years of study at different European universities, he returned home and married Margaret van Ranst, a noble lady of Brabant. He then settled down on his estate at Vilvoorden, near Brussels, where he remained until his death in 1644. Johann Hermann Baas, in his "History of Medicine," characterizes him as a fertile genius in the department of chemistry, but denies that he was a great and independent spirit, outrunning his age, or impressing upon it the stamp of his own individuality. Van Helmont, like many another irregular practitioner, achieved fame by some remarkable cures. It was said of him that his patients never languished long under his care, being always killed or cured within two or three days. He was frequently called to attend those who had been given up by other physicians. And to the latters' chagrin, such patients were often unexpectedly restored to health.[261:1]