432 ON GENERATION. 



the brain or on common sensation; yet neither are these to 

 be presumed as happening without all consciousness. For 

 that which is wholly without sense is not seen to be irri- 

 tated by any means, neither can it be stimulated to motion or 

 action of any kind. Nor have we any other means of distin- 

 guishing between an animate and sentient thing and one that 

 is dead and senseless than the motion excited by some other 

 irritating cause or thing, which as it incessantly follows, so 

 does it also argue sensation. 



But we shall have an opportunity of speaking farther of this 

 matter when we discuss the actions and uses of the brain. 

 Respect for our predecessors and for antiquity at large inclines 

 us to defend their conclusions to the extent that love of truth 

 will allow. Nor do I think it becoming in us to neglect and 

 make little of their labours and conclusions who bore the 

 torch that has lighted us to the shrine of philosophy. I am, 

 therefore, of opinion that we should conclude in this way : we 

 have consciousness in ourselves of five principal senses, by 

 which we judge of external objects; but we do not feel with 

 the same sense by means of which we are conscious that we 

 feel seeing with our eyes, we still do not know by them that 

 we see, but by another sense or sensitive organ, namely, the 

 internal common sensation or common sensorium, by which 

 we examine those things that reach us through each of the 

 external sensoria, and distinguish that which is white from 

 that which is sweet or hard. Now this sensorium commune 

 to which the species or impressions of all the external instru- 

 ments of sensation are referred, is obviously the brain, which 

 along with its nerves and the external organs annexed, is held 

 and esteemed to be the adequate instrument of sensation. 

 And this brain is like a sensitive root to which a variety of 

 fibres tend, one of which sees, another hears, a third touches, 

 and a fourth and a fifth smell and taste. 



But as there are some actions and motions the government 

 or direction of which is not dependent on the brain, and which 

 are therefore called natural, so also is it to be concluded that 

 there is a certain sense or form of touch which is not referred 

 to the common sensorium, nor in any way communicated 

 to the brain, so that we do not perceive by this sense that we 

 feel ; but, as happens to those who are deranged in mind, or 



