We have already explained our reasons for adopting the plan of giving distinct views of the most prevailing medical systems in different articles (see Boerhaavian system), and shall pursue the present meteor from its first spark to its meridian: others may perhaps record its decline or fall. The history of Dr. Brown would not be of importance in this place, were it not necessary to explain some parts of his doctrines. Originally a teacher of Latin, he attended the medical classes by the permission of the different professors; and, as the tutor of his sons in that language, was first connected with Dr. Cullen, to whom he became an useful assistant, and of whose doctrine he was a warm admirer. His great object for a future maintenance when we knew him, was to repeat Dr. Cul-len's lectures in London after his death. Some disagreement turned him to a virulent antagonist, and from hence arose the Brunonian doctrine.

We mean not by this to prejudge or disparage the system: it must rest on its own merits: but, to explain that decided opposition, and the virulent language employed when speaking of the Cullenian doctrines. We. suspect, however, that it may explain the source of some of his own-opinions, without giving him the credit of a very brilliant genius; for, in possession of a system with the arguments in its support, it is not very difficult to say that any part is 'false,' and to wrest the arguments to the opposite opinion. If, however, his system be well founded, it proves his genius to be preeminent, for little was gained by study. We recollect but one author quoted, which is Triller; and, from the manner of the quotation, we should suspect that he was not intimately acquainted with him. The opinions and practice of different authors he could not have been ignorant of, from the lectures he attended; yet it is singular that his practice is so little discriminated, that he seems scarcely to, have visited the sick bed, or attended to the distinguishing symptoms which influence the practical physician in the minuter variations of his conduct.

Dr. Brown, however, started as a self appointed lecturer, and the avowed opponent of the Cullenian system. His doctrine, even more simple than that of the methodists, admitted only of the strictum and laxum, the sthenic and asthenic states, without allowing the union of both. Simplicity is attractive to youth; it is falsely called 'the seal of truth;' and to escape from professorial dogmas, added to the seduction. It is at least certain, that after some months of hesitation Dr. Brown was greatly followed, and his doctrines were echoed in the "Medical Society,"where the Cullenian system had gained a complete victory over the Boer-haavian; and, by the aid of the numerous pupils of that school, was disseminated through Europe, Asia, and America. It was eagerly caught at on all sides; but, by a strange perversion, in escaping from the humoral pathology, many professed Brunonians adopted doctrines es-sentially distinct from those of Brown, supposing that if they were not Boerhaavians, they were of his sect.

Dr. Brown seemed to consider man, not as a being compounded of an organised system to which the principle of life was superadded, but as a machine, to which a certain series of actions and effects is allotted by means of an excitability, differing in degree, but generally, though on the whole imperceptibly exhausting. In fact, it is a flame kept alive by excitements, such as heat, food, passions, etc. which, however, destroy by degrees the pabulum, or, in his language, the excitability. As the machine is merely passive, and the flame kept up by blowing, it cannot be depressed except by an intermission of the blast. It may, however, be exhausted by blowing too violently; or the pabulum, not exhausted by the constant blast, may burn with greater fury on its recommencement. We mean merely to facilitate the reader's conception by our metaphor, not to render the subject ludicrous.

Life, therefore, is a 'forced state;' every thing stimulates; some substances too violently, others not sufficiently: and we thus have two kinds of debility, indirect and direct. In the former case, the strongest stimuli are necessary; in the second, the slightest destroy in consequence of too great irritability. In the gaol fever, for instance, we must give the strongest stimulants: to the man long pent up in darkness, with scanty-food, the light must be moderate, the aliment of the mildest kind, and stimuli of every sort most sparingly administered; as the flame, long repressed, would be roused by the slightest excitement.

Such is the basis of Dr. Brown's system; and for one part of it, accumulated excitability, he deserves the greatest credit. It is a law of the animal economy so general, that the attention to it directs the practitioner in various ways; nor should he, on any occasion, lose sight of its consequence, that too frequent and violent excitements are destructive. It had been well if Dr. Brown had kept it more often in view, particularly in his arrangement of diseases. There is, however, another law of the system connected with this, which has been less adverted to, viz. that excitability, long repressed, is with difficulty, if at all, to be roused by stimulants. Constitutions of this kind are ruined from inactivity; they rust, as we have said, on their hinges; and the Brunonian will not refuse this addition to his system, since it is so connected with his principle, that life is a forced state.

This principle, however, we cannot admit. Life is superadded to organized matter; for organization itself will no more produce it, than the most skilful union of wheels will produce a time piece without its spring. This leads to a fundamental objection to the Brunoman system; that, by giving man in the beginning a determined proportion of excitability, he has no where provided for its renewal, when exhausted. It accumulates from want of exhaustion, but from what source? For, let only an atom be taken from a mountain, and in no way restored, the mountain must in that proportion be diminished, and cannot regain its former bulk. Boerhaave and Cullen felt the difficulty. Boer-haave supplied it by secretion; Cullen, more indistinctly, made it the consequence of collapse, alluding by some remote analogy to the electrical fluid. Brown cut the knot, and, like Jack in the tale, would be as unlike the rogue Peter as possible;' so that there must be no collapse. Brown himself speaks of 'recruiting .the excitability; and his followers, when urged by the difficulty, have either evaded it, or explained in a way not very consistent with the general principle.