Medicine and magic have always been closely associated. Indeed, the greatest name in the history of pharmacy is also what is probably the greatest name in the history of magic--the reference, of course, being to PARACELSUS (1493-1541). Until PARACELSUS, partly by his vigorous invective and partly by his remarkable cures of various diseases, demolished the old school of medicine, no one dared contest the authority of GALEN (130-_circa_ 205) and AVICENNA (980--1037). GALEN'S theory of disease was largely based upon that of the four humours in man--bile, blood, phlegm, and black bile,--which were regarded as related to (but not identical with) the four elements--fire, air, water, and earth,--being supposed to have characters similar to these. Thus, to bile, as to fire, were attributed the properties of hotness and dryness; to blood and air those of hotness and moistness; to phlegm and water those of coldness and moistness; and, finally, black bile, like earth, was said to be cold and dry. GALEN supposed that an alteration in the due proportion of these humours gives rise to disease, though he did not consider this to be its only cause; thus, cancer, it was thought, might result from an excess of black bile, and rheumatism from an excess of phlegm. Drugs, GALEN argued, are of efficiency in the curing of disease, according as they possess one or more of these so-called fundamental properties, hotness, dryness, coldness, and moistness, whereby it was considered that an excess of any humour might be counteracted; moreover, it was further assumed that four degrees of each property exist, and that only those drugs are of use in curing a disease which contain the necessary property or properties in the degree proportionate to that in which the opposite humour or humours are in excess in the patient's system. PARACELSUS' views were based upon his theory (undoubtedly true in a sense) that man is a microcosm, a world in miniature.(1) Now, all things material, taught PARACELSUS, contain the three principles termed in alchemistic phraseology salt, sulphur, and mercury. This is true, therefore, of man: the healthy body, he argued, is a sort of chemical compound in which these three principles are harmoniously blended (as in the Macrocosm) in due proportion, whilst disease is due to a preponderance of one principle, fevers, for example, being the result of an excess of sulphur (_i.e_. the fiery principle), _etc_. PARACELSUS, although his theory was not so different from that of GALEN, whose views he denounced, was thus led to seek for CHEMICAL remedies, containing these principles in varying proportions; he was not content with medicinal herbs and minerals in their crude state, but attempted to extract their effective essences; indeed, he maintained that the preparation of new and better drugs is the chief business of chemistry. (1) See the "Note on the Paracelsian Doctrine of the Microcosm" below.