Nervous complaints may therefore be divided, like all other diseases, into two classes. First, those in which the excitement is increased, or in which it verges to, or has actually reached, the point of predisposition to sthenic disease; Secondly, those in which the excitement is diminished, or in which it verges towards asthenic disease. This last class, as has been done before, may be subdivided into two orders. The first will comprise those diseases in which the excitability is sufficiently abundant, or even accumulated, but where the excitement is deficient from a want of energy in the exciting powers. In the second, there has been no deficiency in the action of the exciting powers; but on the contrary, probably for a considerable time, some of the diffusible stimuli not natural to life have been applied; in this case, the excitability has become exhausted, and a proper degree of excitement cannot be produced by the action of the common exciting powers. No diseases show so clearly the fallacy of trusting to symptoms, as those of the former class. I have met with innumerable cases of this kind, in which, if you were to trust to the patients own description, they laboured under considerable debility; and had it not been for the particular attention I paid to my own case, I should not probably have suspected that a directly opposite state of the system may produce these symptoms. From inheriting a good constitution, and being brought up in the country in a hardy manner, I am so much predisposed to the sthenic state, that I may consider the state of my excitement, as generally, indeed almost always, above the point of health: and unless I live in the most temperate, and even abstemious manner, the excitement is extremely liable to overstep the bounds of predisposition, and fall into sthenic disease. I have had several attacks of this kind of disease; and indeed, I never remember to have laboured under any disease of debility, or diminished excitement.