in the line of Excitability, the diseases which occur must be those of excessive vigour, requiring for their cure the abstraction of stimuli; and beyond this, from 10 to zero, there can occur only diseases of Indirect Debility, which require the use of the most powerful stimuli. Daily observation, however, shews, that in every period of life, from infancy to old age, men may enjoy the most perfect health; and likewise that diseases of increased and of diminished excitement may and do occur in all the stages of human existence. Dr Brown, it is true, has said (Elements, § 26), that every age, and every habit, if the excitement be properly directed, has its due degree of vigour accommodated to it ;" but he has left us in total ignorance with respect to the degree of excitement which constitutes the standard of health in any period of life, with the single exception of middle or adult age.

It seems by no means improbable that the source from which Dr Brown derived his idea of a scale of health and disease, was certain observations made by Dr Cullen in his lectures on Pathology, and which have recently been quoted (see pages 249 and 251), on the standard and the latitude of health, and on the difficulty of fixing precisely the application of the terms of Excitement and Collapse. In a scale constructed in conformity with Dr Cullen's suggestion, health in all periods of life would have been adopted as the middle point; and the deviations on either side, consisting in different states of Excitement and of Collapse (or, in other words, of over and under-excitement), passing through the latitude of health to disease, would have been represented by degrees ascending and descending from that middle point. Whether Dr Brown has improved

upon the suggestion of Dr Cullen, and how far the representations given in his scales of health and disease are reconcilable with one another, consistent with the opinions which they are intended to illustrate, or calculated to assist us in the practice of medicine, must, with these observations, be left to the judgment of the reader to determine.

XI. "Conformably with the division of diseases into Sthenic and Asthenic, there can be only two kinds of Remedies, which always restore the healthy state by opposing deficient stimulus to excessive, and excessive to deficient. The hurtful exciting powers which produce Sthenic discases are the remedies of Asthenic, and those which produce Asthenic, are the remedies of Sthenic diseases. The same debilitating powers which cure any one Sthenic disease, cure every one; the same stimulant powers which remove any Asthenic disease, remove them all." (Elements, § 64, 23, 89. Outlines, § 85, 117.)

It has been already observed, that, according to the principles of the Brunonian theory, all the agents which are capable of acting upon the living body have one common operation, namely, that of producing excitement, or of stimulating, and differ from one another only in the degree in which they produce this effect. The terms Stimulants and Debilitants, therefore, as applied by Dr Brown to his two classes of remedies-those which increase, and those which diminish excitement-must be considered as expressive, not of different kinds of agents, but only of agents producing different degrees of the same mode of action.

Dr Cullen may be said to have prepared the way for this view of the relations of Stimulants and Debilitants, by having remarked in his Lectures on Therapeutics, that" different aliments are of different degrees of stimulant power, and the substituting a weaker in place of a stronger stimulus, is the applying of a sedative to our system." From this quotation it is obvious that the peculiarity of Dr Brown's therapeutical doctrine does not consist in his regarding substances of feeble stimulating powers as Debilitants, for that had been a common belief, but in his denying that there exist any direct sedatives, or primarily debilitating powers in nature. It seems easy to understand, upon his theory, how the taking away stimuli altogether, or the substitution of a weaker for a stronger stimulus, should diminish excitement; and it seems easy, also, to understand how the excessive use of stimuli should ultimately be followed by the same effect. But, it does not seem to be explicable, on the principles of the Brunonian theory, why, during the application of the ordinary supporters of life, the introduction into the general system of particular poisonous substances, or of animal contagions, should, either immediately or after a short lapse of time, be followed, as it frequently is, by a great, perhaps even a fatal, diminution of excitement. If these agents are possessed of only very feeble exciting powers, their application will not be sufficient, independently of the ordinary supporters of life, to prevent that diminution or extinction of excitement which arises from deficiency of stimulant powers, but it should not have any influence in producing or accelerating these states;

and if, on the contrary, we are to believe that these agents possess a high degree of stimulant power, how does it happen that they so frequently prove fatal, without occasioning any marks of that increased excitement, through which, according to Dr Brown's theory, the economy must pass, before death can be produced by the total exhaustion of excitability?

The various therapeutical agents or remedies that are capable of altering or removing the different morbid conditions of the human economy, functional and structural, have very commonly been divided into those which act on the general economy, and those which act only on particular parts of it. By remedies acting on the general economy, medical men seem to have meant chiefly to designate those which act more immediately on the Sanguiferous and Nervous Systems, and which, in consequence of the reciprocal influence of these two systems on one another, and of the dependence of the different organs of the body upon them, come speedily to affect, in a greater or less degree, the condition of the whole economy. By remedies which act on particular parts of the economy, again, are meant those, the primary and principal operation of which seems to be on some of the subordinate organs of the body, and which affect the sanguiferous and nervous systems, and, through them, the other parts of the economy, only in a secondary or indirect manner, or in a less considerable degree.

The states of increased and diminished action or excitement, on which alone Dr Brown conceived all diseases to depend, had long been regarded by medical men, and had particularly been pointed out by Dr

Cullen, as the most frequent morbid conditions to which the different systems and organs of the body, and more especially the organs engaged in circulating the blood, are subject in pyrexial diseases; and those remedial powers, therefore, which diminish excessive, and increase deficient, action of the sanguiferous systemwhether they belong to the class of remedies supposed to act on the economy generally, or to those which act on its particular parts-had, as we shall afterwards have occasion to shew, been justly considered as amongst the most important therapeutical agents. But to the view which Dr Brown has taken of these two morbid conditions as applicable to all diseases, and of the corresponding remedial powers, two obvious and fundamental objections present themselves; the first, that it is impossible to maintain with regard to any single disease, and far less with regard to any class of diseases, that, in all the various circumstances in which that disease, or class of diseases, may present itself, it should be treated solely upon stimulant, or solely upon debilitating, principles; and the second, that remedies do not by any means admit of being all included under the two classes to which Dr Brown has referred them.

1. In judging how far all diseases admit of being divided, as has been done by Dr Brown, into two distinct classes, according as they require a stimulant or a debilitant mode of treatment, it is necessary to keep in mind how much variety, in regard to the states of vigour and debility, a particular case of the same disease may exhibit, both at any given period of its progress in the different functions that may