OF THE NERVES AND MUSCLES. 165 



to demonstrate by one, that which in others may not be essential [as a 

 cause of motion], only fitted for particular purposes ; for the essential 

 must be the same in all. A muscle is the power that acts, or has the 

 power of action in itself. 



Our sensations are our regulators respecting good or evil ; but that 

 is only respecting our bodies. A considerable degree of heat, above 

 100°, e. g., so as to give pain, will coagulate the juices. A pinch that 

 will give pain, will also do mischief to the part. 



Is sensation a sympathy of the brain with the part injured ? 



The senses inform the mincl, the mind in return informs the senses. 

 Sight gives us light and shade; feeling gives us the cause, viz. inequality; 

 and habit of the two makes the last [touch to teach the eye] unneces- 

 sary. When habit of another kind takes place, then light and shade do 

 not give the idea of inequality. A slab of variegated marble does not 

 give the idea of an irregular surface. 



"When a disagreeable sensation takes place joined with a disagreeable 

 reflection, or is accompanied with some disagreeable circumstance, then 

 it becomes too much for the human frame ; for instance, the sawing off 

 a man's leg, or, what is still worse, cutting the human flesh with a 

 rough instrument ; it becomes horrible. 



Pains of the inflammatory kind arise from the nerves of the parts 

 being affected by the parts themselves being affected ; but pains of the 

 nervous kind arise from the nerves themselves being affected, without 

 the parts being affected that these nerves go to. 



The senses are not always regularly proportioned in every person ; 

 some sense being acute, while another is obtuse ; and the contrary in 

 another person. 



The intellect or understanding has an immediate connexion with the 

 senses, and the senses with the intellect. But we find that the different 

 senses have not always the same share of this connexion ; some sense 

 being capable of informing the intellect much more than another, and 

 the intellect using that sense upon every occasion, and neglecting the 

 others. To explain this by example : we find that some people cannot 

 pay attention to what they hear, but search for objects of sight, in order 

 to be informed by the eyes ; these retain what they do see, and can 

 readily reason from it, while they lose the connexion [between the sub- 

 jects addressed to the eye and the ear], and forget the half of what 

 they hear. On the other hand, one shall not be able to pay attention 

 to what is before his eyes ; and, if nothing be said, nothing is noticed ; 

 but he will listen to trifles while grand objects are before his eyes. 



If it were possible to have more senses than what we have, it is very 

 probable we might lose by the gain. We are certainly not capable of 

 managing more variety of sensations than what we have at present, 



