328 THE SENSORIAL FUNCTIONS. 



dissimilar in its spiritual essence from our own? In 

 vain may Descartes and his followers labour to 

 sustain their paradox, that brutes are only auto- 

 mata, — mere pieces of artificial mechanism, insen- 

 sible either to pleasure or to pain, and incapable of 

 internal affections, analogous to those of which we 

 are conscious in ourselves. Their sophistry will 

 avail but little against the plain dictates of the 

 understanding. To those who refuse to admit that 

 enjoyment, which implies the powers of sensation 

 and of voluntary motion, is the great end of animal 

 existence, the object of its creation must for ever 

 remain a dark and impenetrable mystery ; by such 

 minds must all further inquiry into final causes be 

 at once abandoned as utterly vain and hopeless. 

 But it surely requires no laboured refutation to 

 overturn a system that violates every analogy by 

 which our reasonings on these subjects must neces- 

 sarily be guided; and no artificial logic or scholastic 

 jargon will long prevail over the natural sentiment, 

 which must ever guide our conduct, that animals 

 possess powers of feeling and of spontaneous action, 

 and faculties appertaining to those of intellect. 



The functions of sensation, perception, and volun- 

 tary motion require the presence of an animal sub- 

 stance, which we find to be organized in a })eculiar 

 manner, and endowed with very remarkable pro- 

 perties. It is called neurine, or the medullary 

 substance; and it composes the greater part of 

 the texture of the brain, spinal cord, and nerves; 

 organs, of which the assemblage is known by the 

 general name of the nervous system. Certain affec- 

 tions of particular portions of this medullary sub- 

 stance, generally occupying some central situation. 



