30 CONNECTION OF PHYSIOLOGY WITH 



tion is not primarily a disorder of the function of Circulation, but rather of 

 Nutrition, the vascular apparatus being only secondarily affected ; so that no 

 observations on the state of the vessels, and on the movement of the blood 

 through them, give us any real information as to the nature of the morbid 

 action. Further, he is aware that no inferences can be valid, that are 

 founded on experiments made on the cold-blooded Vertebrata, since in them 

 the true Inflammatory state can with difficulty be induced : and also, that the 

 nervous system cannot be an element in the primary phenomena of Inflam- 

 mation, since these are manifested by beings that do not possess it. It will 

 hereafter be pointed out, that, by attention to the principles of Physiology, our 

 knowledge of the real character of this and of many other morbid processes, 

 is now being rapidly increased ; and that it is at the same time acquiring a 

 degree of definiteness, which cannot but lead to important improvements in 

 practice. 



10. As Hygiene, or the art of preserving health, arises out of the science 

 of Physiology, so does the Therapeutic art depend upon the science of Patho- 

 logy ; or, to use language rendered venerable by its antiquity, the ars medendi, 

 to be perfect, must be guided by the ratio medendi. The term Therapeutics, 

 however, is sometimes used to denote that division of the Science of Pathology, 

 which concerns the principles of the application of curative agents to the 

 treatment of disease. There is no real ground, however, for distinguishing 

 this as any other than a section of Pathology ; or for considering the practical 

 use of these principles as any thing but an Art. As Life, in the healthy 

 condition, is known to be maintained by the operation of external agents upon 

 organized tissues endowed with vital properties, so is it found that, in dis- 

 eased states of the system, such a change takes place in the character of these 

 actions, as adapts them to its altered circumstances ; thus, in a febrile con- 

 dition, when any increase of stimulus would be injurious, there is no longer an 

 appetite for food. Moreover, it is found that by the regulation of the natural 

 actions, or the substitution of new ones, the diseased condition may frequently 

 be controlled, and the normal action restored. Hence the inquiry into the 

 curative influence of external agents upon the phenomena of disease, is as much 

 a part of the Science of Pathology, as the study of the influence of the ordinary- 

 vital stimuli, in producing the normal actions of the system, is a division (as it 

 is universally allowed to be) of the Science of Physiology. If this inquiry had 

 terminated in the discovery of general principles, all difficulty would be removed 

 from the Therapeutic art, as soon as the perplexities of diagnosis had been over- 

 come ; and, in proportion as such are approached, and our knowledge of the 

 essential nature of diseased actions is extended, will be the facility and the 

 success of our curative treatment. 



11. In the mean time the practitioner must be content to follow a middle 

 course. His aim must be to avoid, on the one hand, confiding too exclusively 

 in general principles, however stable and comprehensive he may imagine 

 them to be, until he is satisfied that he knows, not only the principle itself, 

 but the subordinate laws which regulate or modify its application to individual 

 cases. Long after the highest laws of motion had been established by New- 

 ton, no astronomer could, on the faith of them, have predicted the situation of 

 a planet, with more than an approximation to certainty ; the law of attraction 

 had to be applied in numberless modes not contemplated by its discoverer, 

 before perfect accuracy could be attained. There is great danger, then, in 

 the present state of the science of Pathology, in trusting to principles which we 

 may consider unassailable, as our sole guides in the practice of our art ; and 

 hence it is not always the scientific practitioner, as he is emphatically termed, 

 who is the most successful in his treatment. On the other hand, to apply a 

 particular mode of treatment to a particular set of symptoms, without inquiring 



