it. Suppose, also, a pipe to be placed in the back of the chimney, through which a constant supply of fresh fuel was gradually let down into the grate to repair the waste occasioned by the flame kept up by the air machine.

"The grate will represent the human frame; the fuel in it the matter of life, the excitability of Dr. Brown, and the sensorial power of Dr. Darwin. The tube behind, supplying fresh fuel, will denote the power of all living systems constantly to regenerate, or reproduce excitability ; while the air machine, of several tubes, denotes the various stimuli applied to the excitability of the body; and the flame drawn forth in consequence of that application, represents life, the product of the exciting powers, acting upon the excitability.

"As Dr. Brown has defined life to be a forced state, it is fitly represented by a flame, forcibly drawn forth from fuel, little disposed to combustion, by the constant application of streams of air poured into it by the different tubes of a machine. If some of these tubes are supposed to convey pure, or dephlogisticated air, they will denote the highest class of exciting powers-opium, musk, camphor, spirits, wine, tobacco, &c., the diffusible stimuli of Dr. Brown, which bring forth for a time a greater quantity of life than usual, as the blowing in of pure air into a fire will temporarily draw forth an uncommon quantity of flame. others of the tubes be supposed to convey common, or atmospheric air, they will represent the ordinary exciting powers, or stimuli, applied to the human frame, such as heat, light, air, food, drink, &c., while such as convey impure or inflammable air, may be used to denote what have formerly been termed sedative powers, such as poisons, contagions, miasmata, foul air, &c.

It

"The reader will now probably be at no loss to understand the seeming paradox of the Brunonian system. That food, drink, and all the powers applied to the body,

though they support life, yet consume it; for he will see that the application of these powers, though it brings forth life, yet, at the same time, wastes the excitability, or matter of life, just as the air blown into the fire brings forth more flame, but wastes the fuel or matter of life. This is conformable to the common saying, 'The more a spark is blown, the brighter it burns, and the sooner it is spent.' A Roman poet has given us, without intending it, an excellent illustration of the Brunonian system, when he says,

'Balnea, vina, Venus consumunt corpora nostra,

Sed vitam faciunt balnea, vina, Venus.'

Wine, warmth, and love our vigour drain,

Yet wine, warmth, love our life sustain.'

"Equally easy will it be to illustrate the two kinds of debility termed direct and indirect, which, according to Brown, are the causes of all diseases. If the quantity of stimulus, or exciting power, is proportionate to the quantity of the excitability—that is, if no more excitement is drawn forth than is equal to the quantity of excitability produced, the human frame will be in a state of health, just as the fire will be in a vigorous state when no more air is blown in than is sufficient to consume the fresh supply of fuel constantly poured down by the tube behind. If a sufficient quantity of stimulus is not applied, or air not blown in, the excitability in the man, and the fuel in the fire, will accumulate, producing direct debility; for the man will become weak, and the fire low-carried to a certain degree, they will occasion death to the first, and extinction to the last. If, again, an over-proportion of stimulus be applied, or too much air blown in, the excitability will soon be exhausted, and the matter of fuel almost spent. Hence will arise indirect debility, producing the same weakness in the man and lowness in the fire as before, and equally terminating, when carried to a certain degree, in death and extinction.

"As all the diseases of the body, according to Dr. Brown, are occasioned by direct or indirect debility, in consequence of too much, or too little stimuli, so all the defects of the fire must arise from direct or indirect lowness, in consequence of too much or too little air blowing into it. As Brown taught that one debility was never to be cured by another, but both by the more judicious application of stimuli; so will be found the case in treating the effects of the fire. If the fire has become so low, or the man weak, by want of the needful quantity of stimulus, more must be applied,—but very gently at first, and increased by degrees, lest a strong stimulus, applied to the accumulated excitability, should produce death, as in the case of a limb benumbed by cold (that is, weakened by the accumulations of its excitability, in consequence of the usual stimulus heat), and suddenly held to the fire, which we know from experience is in danger of mortification; or, as in the case of the fire, become very low by the accumulation of the matter of fuel which the feeble flame, assailed by a sudden and strong blast of air, would be overpowered and put out, instead of being nourished and increased. Again, if the man or the fire have been rendered indirectly weak by the application of too much stimulus, we are not suddenly to withdraw the whole, or even a great quantity, of the exciting powers, or air-for then the weakened life and diminished flame might sink entirely; but we are, by little and little, to diminish the overplus of stimulus, so as to enable the excitability or matter of fuel gradually to recover its proper proportion. Thus, a man who has injured his constitution by the abuse of sprituous liquors, is not suddenly to be reduced to water alone, as is the practice of some physicians, but he is to be treated as the judicious Dr. Pitcairn, of Edinburgh, is said to have treated a highland chieftain, who applied for advice in this situation. The doctor gave him no medicines, and only exacted a pro

mise of him that he would every day put in as much wax into the wooden queich, out of which he drank his whiskey, as would receive the impression of his arms. The wax thus gradually accumulating, diminished daily the quantity of whiskey till the whole queich was filled with wax; and the chieftain was thus gradually, and without injury to his constitution, cured of the habit of drinking spirits. These analogies might be pursued farther, but my object is solely to furnish some general ideas to prepare the reader for entering more easily into the Brunonian theory, which I think he will be enabled to do after perusing what I have said.

"The great excellence of that theory, as applied not only to the practice of physic, but to the general conduct of the health, is, that it impresses upon the mind a sense of the impropriety and danger of going from one extreme to another. The human frame is capable of enduring great varieties, if time be given it to accommodate it to different states; all the mischief is done in the transition from one state to another. In a state of low excitement, we are not rashly to induce a state of high excitement, nor when elevated to the latter are we suddenly to descend to the former, but step by step, and as one who, from the top of a high tower descends to the ground. From hasty and violent changes the human frame always suffers; its particles are torn asunder, its organs injured, the vital principle impaired, and disease, often death, is the inevitable consequence.

"I have only to add, that though in this illustration of the Brunonian system, written several years ago, I have spoken of a tube constantly pouring in fresh fuel, because I could not otherwise convey to the reader a familiar idea of the power possessed by all living systems to renew their excitability when exhausted, yet it may be proper to inform the student, that Dr. Brown supposed every living system to have received at the beginning its determinate proportion of excitability; and there

fore, although he spoke of the exhaustion, augmentation, and even renewal of the excitability, I do not think it was his intention to induce his pupils to think of it as a kind of fluid substance existing in the animal, and subject to the law by which such substances are governed. According to him, excitability was an unknown somewhat subject to peculiar laws of its own, and whose different states we were obliged to describe (though inaccurately), by terms borrowed from the qualities of material substances."

This full and lucid explanation affords ample materials for forming a dispassionate opinion on the system of Brown. Such a judgment it was difficult to arrive at, when it was first promulgated, as so much of the personality of the man entered into the impression made by his doctrines; and although there might be Brunonians, who were not extravagant in their views and reckless in their advice, we can scarcely class the founder of the school in this category. We frequently see disciples outheroding their master, but John Brown's prescriptions seem a caricature of his system. For example, here is one written in reference to a hypochondriac patient, about whose case he was consulted:-"For breakfast, toast and rich soup made on a slow fire, a walk before breakfast, and a good deal after it; a glass of wine in the forenoon, from time to time; good broth or soup to dinner, with meat of any kind he likes, but always the most nourishing; several glasses of port or punch to be taken after dinner, till some enlivening effect is perceived from them, and a dram (of whiskey?) after everything heavy; one hour-and-ahalf after dinner, another walk; between tea-time and supper, a game with cheerful company at cards or any other play, never too prolonged; a little light reading; jocose-humourous company, avoiding that of popular Presbyterian ministers and their admirers, and all hypocrites and thieves of every description Lastly, the