28 CONNECTION OF PHYSIOLOGY WITH 



to be regarded as medical, e. g., the regulation of diet, temperature, &c.; but 

 this employment of it is not strictly correct, such treatment being properly a 

 part of Therapeutics, an art which stands in the same relation to Hygiene, 

 that Pathology bears to Physiology. In proportion as the science of Physio- 

 logy is perfected, will the simplicity and certainty of its practical applications 

 increase; and though we may not anticipate a return of patriarchal longevity, 

 yet the experience of the last century has amply shown, that every general 

 increase of attention to its simple and universally-acknowledged truths, is 

 attended with a prolongation of life, and contributes to that not less important 

 object its emancipation from disease. Hence the establishment of the rules 

 of Hygiene may be considered as the most direct practical benefit, afforded by 

 the pursuit of Physiological science. 



7. In the assistance which it affords, however, in the establishment of the 

 principles of Pathology, the importance of Physiology is by no means inferior; 

 and it is surprising how much the relation of the two has been neglected. 

 That the knowledge of the normal actions of a living system is essential to 

 success, in the investigation of the causes and mode of cure of its irregulari- 

 ties, seems almost a self-evident proposition. We should all think it absurd 

 for a person to attempt to repair a watch or a steam-engine that might be 

 acting wrongly, without being acquainted with the uses of the several parts of 

 its structure, both singly and in combination with each other. He might 

 have such an acquaintance with their form and mechanical arrangement, as 

 might enable him to delineate them, or even to construct the counterpart of 

 the whole machine, without being able to put it into successful operation. 

 Just so it is with an anatomist, who regards the mere acquaintance with the 

 structure of the human body as a sufficient guide in the treatment of disease. 

 But this is really of little assistance in any thing but surgical operations ; 

 that which we require to know, for the rectification of morbid phenomena, 

 being the normal history of those phenomena, and the conditions on which 

 they are dependent. The neglect of physiological science as an adjunct to 

 the ars medendi, may probably be in part attributed to the facility with which 

 striking curative effects may often be produced, by the application of empi- 

 rical rules only. Thus a person usually healthy, who is suffering from head- 

 ache, feverishness and constipation, the effects of an overloaded alimentary 

 canal, may be pretty certainly relieved by a brisk purge ; or a stout child, 

 w r ho is suffering from cough, tightness of the chest, and heat and dryness of 

 skin, resulting from recent exposure to cold and damp, by a strong dose of 

 an antimonial. These are results with which every tyro is well acquainted ; 

 they are based upon ordinary experience, and, if applied without further con- 

 sideration of their rationale, are strictly empirical. The case might be com- 

 pared to that, in which a person unacquainted with the construction or prin- 

 ciples of action of a watch or a steam-engine, alters its rate of movement, by 

 shifting a lever or opening a cock. But, though usually successful, excep- 

 tional cases will occur, in which unexpected results will follow ; and the 

 merely empirical practitioner is baffled and confounded. For these, some- 

 thing more is requisite ; and no treatment can be successful, otherwise than 

 by an accidental coincidence, in which the causes of the derangement are not 

 carefully inquired into, and their operation understood. And how can their 

 operation, in producing a disturbance of the system, be comprehended, when 

 its regular actions are not even known, far less, their principles ascertained? 



8. The study of Physiology, being the inquiry into the phenomena of nor- 

 mal life and the conditions of those phenomena, requires a knowledge of the 

 two sets of causes which must be concerned in them, the organized struc- 

 ture or mechanism, possessed of certain properties, and the agents or sti- 

 muli, by whose operation on this mechanism its properties are made to de- 



