THE SYNTHETICAL METHOD. 481 



terial machines put in motion by simple mechanical laws. 

 In denying perception to animals, he certainly avoided 

 the singular consequence of materialism, which, by invest- 

 ing matter with that power, denies the unity of the perci- 

 pient. There is also no impossibility in the same actions 

 of a man and a brute resulting by the same medium, nerves, 

 from different causes. But that a uniform mechanical 

 law should produce effects varying according to circum- 

 stances, as we perceive them in the generality of animals, 

 is perfectly unintelligible, and has occasioned the Carte- 

 sian hypothesis to be generally regarded as one of the 

 most revolting assumptions of philosophy. If any zoolo- 

 gist, however, be an advocate for the necessity of human 

 actions, I do not see how he can consistently maintain the 

 superiority of man over other animals, without being either 

 a materialist or a Cartesian. 



4. We proceed, as often happens in matters of belief, 

 from one extreme to the other, and now have to state, that 

 by some persons every animal has been accounted not only 

 to be acted upon by an immaterial sentient principle, but 

 to be endowed with free agency as well as man. If, indeed, 

 nervous matter be necessarily indicative of the presence 

 of an immaterial free agent, no line can well be drawn to 

 separate one part of the animal kingdom from the other ; 

 and we must thus, with free agency, allow responsibility 

 and a future state even to that principle which animates 

 the gelatinous pulp of an ascidia or polype. Yet this 

 conclusion, which to me is even more disagreeable than 

 that of Descartes, has been entertained by some of the 

 most acute philosophers that have ever existed. It appears 

 also to lead inevitably and directly to a ridiculous idea of 

 Krause, who has seriously asserted, not only the presence 



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