not ripe, but which, in his time, was so singularly rash and immature, that nothing can explain its adoption by a man of such vigorous understanding, except the circumstance of his living in a country in which that peculiar method reigned supreme.

It must, however, be admitted, that Cullen wielded the method with great ability, especially in his application of it to the science of pathology, to which it was far better suited than to the art of therapeutics. For, we must always remember, that the science which investigates the laws of disease, is quite a different thing from the art which cures it. The science has a speculative interest, which is irrespective of all practical considerations, and which depends simply on the fact, that, when it is completed, it will explain the aberrations of the whole organic world. Pathology aims at ascertaining the causes which determine every departure from the natural type, whether of form or of function. Hence it is, that no one can take a comprehensive view of the actual state of knowledge, without studying the theoretic relations between pathology and other departments of inquiry. To do this, is the business, not of practical men, but of philosophers, properly so-called. The philosophic pathologist is as different from the physician, as a jurist is different from an advocate, or as an agricultural chemist is different from a farmer, or as a political economist is different from a statesman, or as an astronomer, who generalizes the laws of the heavenly bodies, is different from a captain, who navigates his ship by a practical application of those laws. The two sets of functions may be united, and occasionally, though very rarely, they are, but there is no necessity for their being so. While, therefore, it would be absurdly presumptuous for an unprofessional person to pass judgment on the therapeutical system of Cullen, it is perfectly legitimate for any one, who has studied the theory of these matters, to examine his pathological system; because that, like all scientific systems, must be amenable to general considerations, which are to be taken, partly from the adjoining

sciences, and partly from the universal logic of philosophic method.

It is from this latter, or logical, point of view, that Cullen's pathology is interesting for the purposes of the present chapter. The character of his investigations may be illustrated by saying, that his method in pathology is analogous to that which Adam Smith adopted at the same time, though in a very different field. Both were deductive; and both, before arguing deductively, suppressed some of the premisses from which they reasoned. That this suppression is the key to Adam Smith's method, and was an intentional part of his plan, I have already shown; as also that, in each of his two works, he supplied the premisses in which the other work was defi cient. In this respect, he was far superior to Cullen. For, though Cullen, like Smith, began by mutilating his problem in order to solve it more readily, he, unlike Smith, did not see the necessity of instituting another and parallel inquiry, which should complete the scheme, by starting from the premisses that had been previously

omitted.

What I have termed the mutilation of the problem, was effected by Cullen in the following manner. His object was, to generalize the phenomena of disease, as they are exhibited in the human frame; and it was ob vious to him, as to every one else, that the human frame consists partly of solids and partly of fluids. The peculiarity of his pathology is, that he reasons almost entirely from the laws of the solids, and makes so little account of the fluids, that he will only allow them to be the indirect causes of disease, which, in a scientific view, are to be deemed strictly subordinate to the direct causes, as represented by the solid constituents of our body.21

214 This idea runs through the whole of his writings. In the following passage, it is more succinctly stated than in any other: "In pathology, and in the prognosis of particular diseases, it is absolutely necessary to enter into the distinction of these causes. I call the one direct causes, those which act upon the nervous system directly; and the other indirect causes, those which produce the same effect, but by destroying those organs which are necessary to the support of the excitement, viz. the whole system of circulation." Cullen's Works, vol. i. p. 135. Even this passage, clear as

This assumption, though false, was perfectly justifiable, since, by curtailing the problem, he simplified its study; just as Adam Smith, in his Wealth of Nations, simplified the study of human nature, by curtailing it of all its sympathy. But this most comprehensive thinker was careful, in his Theory of Moral Sentiments, to restore to human nature the quality of which the Wealth of Nations had deprived it; and, by thus establishing two different lines of argument, he embraced the whole subject. In the same way, it was incumbent on Cullen, after having constructed a theory of disease by reasoning from the solids, to have constructed another theory by reasoning from the fluids; so that a coördination of the two theories might have raised a science of pathology, as complete as the then state of knowledge allowed.215 But to this, his mind was unequal. Able though he was, he lacked the grasp of intellect which characterized Adam Smith, and which made that great man perceive, that every deductive argument, which is founded on a suppression of premisses, must be compensated by a parallel argument, which takes those premisses into account.216 So little was Cullen aware of this, that, having built up that system of pathology which is known to medical writers as Solidism, he never took the pains to accompany it by another system, which gave the first rank to the fluids. On the contrary, he believed that his plan was complete and exhaustive, and that what is termed Humoral Pathology was a fiction, which had too long usurped the place of truth.217

it seems, can only be rightly interpreted by taking the context into consideration.

215 For, as is truly observed by probably the greatest pathologist of our time, "Humoral pathology is simply a requirement of common practical sense; and it has always held a place in medical science, although the limits of its domain have, no doubt, been variously circumscribed or interpreted at different times. Of late years, it has met with a new basis and support in morbid anatomy, which, in the inadequacy of its discoveries in the solids to account for disease and death, has been compelled to seek for an extension of its boundary through a direct examination of the blood itself." Rokitansky's Pathological Anatomy, vol. i. p. 362, London, 1854.

216 Unless, as is the case in geometry, the premisses, which are suppressed, are so slight as to be scarcely perceptible.

217 He was so indignant at the bare idea of a humoral pathology, that even Hoffmann, who before himself was the most eminent advocate of

Several of the views advocated by Cullen were taken from Hoffmann, and several of the facts from Gaubius; but that his pathology, considered as a whole, is essentially original, is evident from a certain unity of design which is inconsistent with extensive plagiarism, and which proves that he had thoroughly thought out his subject for himself. Without, however, stopping to inquire how much he borrowed from others, I will briefly indicate a few of the salient points of his system, in order to enable the reader to understand its general character.

According to Cullen, all the solids in the human body are either simple or vital. The simple solids retain, after death, the properties which they possessed during life. But the vital solids, which form the fundamental part of the nervous system, are marked by properties, which disappear directly death occurs.218 Hence, the simple solids, having fewer functions than the vital, have also fewer diseases; and the maladies to which they are liable admit of easy classification.219 The real difficulty lies in the vital solids, because on their peculiarities the whole nervous system depends, and nearly all disorders are immediately due to changes in them. Cullen, therefore, made the nervous system the basis of his pathology; and, solidism, fell under his displeasure for allowing some little weight to the humoral doctrines. He says that Hoffmann "has not applied his fundamental doctrine so extensively as he might have done; and he has everywhere intermixed an humoral pathology, as incorrect and hypothetical as any other." Cullen's Works, vol. i. p. 410. At p. 470, "I have, therefore, assumed the general principles of Hoffmann. And, if I have rendered them more correct, and more extensive in their application, and, more particularly, if I have avoided introducing the many hypothetical doctrines of the Humoral Pathology which disfigured both his and all the other systems that have hitherto prevailed, I hope I shall be excused for attempting a system, which, upon the whole, may appear new."

218 "The solid parts of the body seem to be of two kinds: one whose properties are the same in the dead as in the living, and the same in the animate as in many inanimate bodies; the other, whose properties appear only in living bodies. In the last, a peculiar organization, or addition, is supposed to take place; in opposition to which the first are called the simple solids. Of these only, we shall treat here; and of the others, which may be called vital solids, being the fundamental part of the nervous system, we shall treat under that title in the following section." Cullen's Works, vol. i. p. 10.

219 These diseases are laxity, flaccidity, &c. See the enumeration of 'the diseases of the simple solids," in Cullen's Works, vol. i. p. 14.

in speculating on its functions, he assigned the chief place to an occult principle, which he termed the Animal Power, or Energy, of the brain.220 This principle acted on the vital solids. When the principle worked well, the body was healthy; when it worked ill, the body was unhealthy. Since, then, the state of the vital solids was the main cause of disorder, and since the Energy of the brain was the main cause of the state of the vital solids, it became important to know what the influences were which acted on the Energy, because in them we should find the beginning of the series. Those influences were divided by Cullen into physical and mental. The physical were, heat, cold, and effluvia, the three most potent of the material disturbers of the human frame.221 The mental influences, which excited the brain to act on the solids, were comprised under six different heads, namely, the will, the emotions, the appetites, the propensities, and, finally, the two great principles of habit and of imitation, on which he, with good reason, laid considerable stress.222 In arguing from these mental causes, and in generalizing the relations between them and the sensations of the body, he, faithful to his favourite method, proceeded deductively from the metaphysical principles then in vogue, without inquiring inductively into their validity, such an induction being, he thought, no part of his duty.223 He was

220 Cullen's Works, vol. i. pp. 65, 600, vol. ii. p. 364. Dr. Thomson, who had access to papers and lectures of Cullen's, which have never been published, says (Life of Cullen, vol. i. p. 265), “His speculations with regard to the different functions of the nervous system, but more particularly with regard to that of the Animal Power or Energy of the brain, were incorporated with every opinion which he taught concerning the phenomena of the animal economy, the causes of diseases, and the operation of medicines; and they may be said to constitute a most important part, if not the sole basis, of that system of the Practice of Physic, which he made the subject of prelection, as well as of study, for a period of nearly forty years, before he ventured to give it to the public." I should mention, that Cullen, under the term 'brain,' included the contents of the vertebral column as well as of the cranium.

221 Cullen's Works, vol. i. pp. 40, 546, 558, 648, vol. ii. p. 321.

Cullen's Works, vol. i. pp. 86, 91, 100, 101, 103, 115, 116, 553, 592, vol. ii. pp. 35, 366. Compare the summary of causes in Thomson's Life of Cullen, vol. i. p. 289.

223 He says (Works, vol. i. pp. 31, 32), "Whoever has the smallest tincture of metaphysics will know the distinction pointed at here between the