people in this department of medical science. In this collection, more than 1400 medicinal and dietetical articles are described, many of them no doubt in nearly the same terms as they had been noticed by Dioscorides and Galen, but of original matter relative to substances then for the first time introduced into the practice of medicine, there is no lack; and it is only to be regretted that a proper key to these stores is still a desideratum which it is to be feared will not soon be supplied. Ebn Baithar’s list of medicinal substances, however, is far more copious than those of the other Arabians, who in general follow closely in the footsteps of the Greek authorities, and seldom supply anything very original of their own. For example, the Materia Medica of Rhases contains only 765 articles, and that of Avicenna only 747, which it is to be remarked, is a smaller number than is contained in the work of Dioscorides, wherein Alston states that he counted above 90 minerals, 700 plants, and 168 animal substances, making 958 in all. This is nearly triple the number of simples contained in the Materia Medica of the Edinburgh Dispensatory at the present day, which amount only to 341 articles; so that if this branch of medical science has received any material improvement in modern times, it must arise principally from our superior accuracy in estimating the virtues of the substances now in use, or in making more ingenious compositions of their elementary ingredients. At all events, it is quite clear that the Greek, Roman, and Arabian physicians were amply provided with medicines of every possible character, and there is no reason to suppose that they were in anywise behind us in the skilful management of them. It has been affirmed, indeed, in some late publications which we have seen, that the ancients had never classified the articles in the Materia Medica according to the nature of their actions; but this we need scarcely assure the reader is a very erroneous account of the matter: and in proof of this we could have wished, if our limits had permitted us, to have introduced here some of the classified lists of medicinal substances as given by the ancient authorities, and more especially those of Aëtius and Serapion. Verum hæc ipse equidem, spatiis inclusus iniquis Prætereo, atque aliis post me memoranda relinquo. We have mentioned above that Aëtius’s account of the general principles of the Materia Medica is particularly excellent, and we have now to add, that as it is sufficiently explicit to convey a distinct idea of the Galenical system, and is contained within moderate limits when compared with the full and lengthy exposition of it given by Galen himself, we shall give that of Aëtius entire, and confine our annotations almost solely to it in the present instance:— “_On the Powers of Simple Medicines._