MATERIA medica. It is a subject of cu. riosity rather than of use, to enquire by what means mankind are induced, in the first in stance,to have recourse to substances,when in a state of disease, which, for the most part, they abhor and fly from when in a state of health ; and how they came to dis cern that in these substances chiefly, nature has treasured up the remedies of sick ness, the restoratives of a vitiated or de bilitated constitution. From whatever source this knowledge has been derived, we feel it daily to be a knowledge of a very important character, and we are sen sible of its having been very generally diffused at a very early period of ancient history. Accident, in the first instance, and experience confirming the result of some fortunate discovery, were perhaps the chief foundation of therapeutic science in the simplest and rudest ages of the world. Yet the whole can by no means be traced to this source, for the general fallacy of experience is sufficient to prove, that it has had but a very small share in establishing the virtues which have been as cribed to most medicines ; and it was pro bably from a too frequent disappointment in practice, from palpable proof of the un certainty of those remedies which are re commended by the ancients, that physi cians in times comparatively modern have been induced to seek for means, not only for ascertaining more exactly the quali ties of established medicines, but of in vestigating the virtues of substances alto gether new and untried.
Hence unquestionably the union of che mistry with the art of healing ; for among the earliest chemists we meet with the first attempts at departing from the usual catalogue of medicines in pursuit of a new list. Paracelsus led the way, by introduc ing the absurd notion of astral influences and of signatures ; to which succeeding and more rational chemists suggested the utility of a chemical analysis. The doc trine of astral influences and of signatures, has been altogether exploded for a long time, though we still trace certain vesti ges of its former existence in many of our latest publications on the Materia Medica. Chemical analysis, as it ought to do, has completely triumphed over the two for mer systems, and is daily extending its enquiries. To arts, manufactures, and commerce, these enquiries have been pre eminently useful, nor have they been without their benefit to medicine ; yet the benefit resulting from this last ap. plication has by no means been equal to that which has resulted to the two former.
The means then resorted to in the pre sent day for determining substances to be remedial or medicinal, or, in other words, the previous steps to their introduction in to the Materia Medica, are their own sen sible qualities, their botanical affinity, their chemical examination, and general experience.
Having introduced them into the medi cal catalogue, our two next subjects of consideration are, their classification or arrangement, and the best mode of em ploying them, whether simply, and on ac count of their own specific virtues, or in connection with other substances, by which their proper qualities are so inter mixed with the qualities of the other sub stances employed, as to acquire an in creased, a diminished, or altogether a new action ; and consequently to be pro ductive of a different result.
The former consideration alone be longs, strictly speaking, to the present article ; the latter constituting the proper subject of pharmacy or compound medi cine. For the theory and practice, there fore, of combining and compounding me dicinal substances, we refer our readers to the article PHARMACY; and shall here confine ourselves, as strictly as we may be able, to the materials actually em ployed in medicine, on account of their own supposed inherent virtues, and which for the most part are denominated simples.
What ought to be classification of these materials ? This is a question which has often been agitated, and almost as often answered in a different manner: whence the arrangement of different writers is as different as possible, as founded upon some supposed superior advantage, or even the mere fancy of the author him self. The most simple arrangement is that of an alphabetic form, and it has taken place in most of the dispensatories and pharmacopoeias of modern times ; but it conveys no practical information, indi cates no specific virtue, communicates no scale of comparative power. Another arrangement is that founded upon the quarter or kingdom from which the mate rial is derived ; and of course under this system the Materia Medica is divided into the three grand classes of animal, vegeta ble, and mineral substances. Yet this ar rangement does not appear to be of much more advantage than the preceding ; the plan is even less simple, and the know ledge it communicates is too trivial to be of any importance. Another, therefore, and a better distribution is founded upon the sensible and more obvious qualities of the substances employed in medicine ; from their being acid, absorbent, gluti nous, unctuous, astringent, saccharine, acrid, aromatic, bitter, emetic or cathartic. For this classification we are indebted to Cartheuser ; it is highly ingenious, and so far as it is applicable, of considerable utility. But it labours under the defect of being incapable of general application.