354 Medicine. [Chap. IV. 



lishing the systems of others than in erecting his 

 own. 



l>;e next system which demands attention, in 

 the order of time, is that of Dr. John Brown of 

 Edinburgh*. This original, eccentric, nnfortnnate 

 man framed a physiological and pathological theory, 

 which, amidst great erronrs, inconsistencies, and 

 contradictions, contains many vigorous conceptions, 

 of truth and nature, and some which it is probable 

 the improvements of future times will serve much 

 further to elucidate and confirm. 



Brown assumed, as the foundation of his system, 

 the existence of an unknown principle, on which, 

 when acted upon by stimuli, all the phenomena of 

 life, health, and disease, depend, and which he de~ 

 nominated excitability. This excitability he be- 

 lieved to vary in different animals, and in the same 

 anim.al at ditferent times. As it is more intense,- 

 the animal is more susceptible of the action of ex~ 

 citing powers. Exciting powers, or stimuli, may 

 be referred to two classes ; either external, as heat, 

 food, wine, poisons, contagions, the blood, secreted 

 fluids, and air; or interna], such as the functions of 

 the body itself, muscular motion, thought, emotion, 

 and passion. Excitability produces no effect, or 



* Dr. John Brown was born in the village of Dunse, in Scot- 

 land, in ihe year I7«'5. His parents were in very Immble life:. 

 and through his whole career he maintained a struggle with po- 

 verty. He began to teach medicine by public lectures in Edin- 

 burgh, about the year 1777 •' he removed to London in l78Ci, 

 where he died in 1783, in the 53d year of his age. Pie v. as un- 

 doubtedly a man of great and original genius, and ^of considerable 

 ac(|uiremeht,s, but tlie unfortunate victim of folly and intempe- 

 rance. His Ehmenta MediciiKV were first pubhshed by him id 

 Latin, and afterwards trani>lated 1 y the author into English. 



