HISTORY OF MEDICINE. 377 



they set about the dissection of the human body itself. This 

 was especially done by Erasistratus and Herophilus, considera- 

 ble names in physic. Both of them were Dogmatists, but they 

 pursued different courses. 



Erasistratus made many discoveries in anatomy, and many 

 new attempts in physiology, but he was not judicious enough to 

 perceive that these last were conjectures only, and not yet so 

 well founded as to admit of application to practice. Erasistra- 

 tus, however, unhappily overlooked this, and even founded 

 upon his conjectures the general rules of his practice. Thus 

 from theory he avoided bleeding and purging, two of the most 

 powerful remedies then known, and at all times since acknow- 

 ledged to be such. This is always a strong mark of the abuse 

 of theory, when it excites too strongly either attachments or pre- 

 judices with regard to general remedies. Most of these have 

 been established, by repeated experience, as useful in certain 

 cases, and it is at the same time certain that none of them can 

 either be admitted as universally useful, or be rejected as 

 universally hurtful. Botallus, many ages afterwards, went 

 to the opposite extreme in making bleeding an universal re- 

 medy ; but the chemists, his cotemporaries, went into a more 

 considerable error still, in universally rejecting it as altogether 

 hurtful. The same was the error of Erasistratus, and it was 

 a very manifest abuse of theory. Erasistratus, however, has 

 given us another example of the abuse which theory is cap- 

 able of, seemingly more innocent in the physician, but per- 

 haps not less pernicious to patients. To understand it you 

 must observe that theory, in general, is more fitted to raise 

 doubts and fears than to remove them, and therefore it very 

 often gives irresolution and timidity in practice ; it takes away 

 from our confidence in experience, and makes us avoid all the 

 most powerful remedies, all those whose operation is sometimes 

 violent, and whose effects, therefore, may upon some occa- 

 sions be very bad, though upon others very good. It is pro- 

 bable that it was this theoretical timidity which made Erasistratus 

 entirely avoid purging, as it had been then common to use pur- 

 gatives of a violent kind ; and it was probably the same temper 

 that induced Erasistratus to employ very few drugs of any kind ; 



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