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and odour, and taste, are not felt in the organs they impress ; it is the 

 sensitive centre that sees, and hears, and smells, and tastes. You have 

 only to interrupt, by compression of the nerves,, the communication be- 

 tween the organs and the brain, and all consciousness of the impressions 

 of objects, all sensation is suspended. 



The torturing pains of a whitlow cease, if you bind the arm so strongly 

 as to compress the nerve which carries the sensation to the brain. A 

 living animal, under experiments, suffers nothing from the most cruel 

 laceration, if you have first cut the nerves of the parts on which you are 

 operating. To conclude, the organs of sense, and the nerves which com- 

 municate between them and the brain, shall have suffered no injury, 

 shall be in perfect state for receiving and transmitting the sensitive im- 

 pression, yet no phenomena of sensation can take place, if the brain be 

 deceased; when it is compressed, for instance, by a collection of fluid, or 

 by a splinter from the skull in a wound of the head. This organ is, 

 therefore, the immediate instrument of sensations, of which impressions 

 made on the others are only the occasional causes. This modification of 

 sensibility, which serves to establish the relations of the living being, with 

 objects without, would be correctly denominated cerebral sensibility; but 

 that even in animals without brain, or distinct nervous system, it is very 

 manifest. The sensibility, in virtue of which the polypus dilates his ca- 

 vity, for the admission of his prey, and contracts itself to retain it, is in 

 fact, quite distinct from that sensibility of nutrition, by which its substance 

 is enabled to take to itself nutritious juices. 



The brain, as Cabanis has well expressed it, acts upon the impression 

 transmitted by the nerves, as the stomach upon the aliments it receives 

 by the oesophagus : it does, in its own way, digest them : set in motion by 

 the impulse it receives, it begins to re-act; and that re-action isthe/zer- 

 cefitive sensation, or perception. From that moment, the impression be- 

 comes an idea, it enters as an element into thought 5 and becomes sub- 

 ject-to the various combinations that are necessary to the phenomena 

 of understanding*. 



CLIV. Our sensations are nothing but modifications of our being; they 

 are not qualities of the objects : no body has colour to the blind from 

 birth: the rose has lost its most precious quality to him who has lost his 

 smell : he knows it from the anemone, only by its colour, its figure, 8cc. 

 We perceive nothing but within ourselves. It is only by habit, only by 

 applying different senses to the examination of the same object, that we 

 are at least able to separate it from our own existence ; to conceive of it 

 as distinct from ourselves, and from the other bodies with which we are 

 acquainted ; in a word, to refer to outward objects the sensations that 

 take place within ourselves. Our ideas come to us, only by the senses; 

 there are none innate as was imagined till the time of Locke, who has al- 

 lotted to the refutation of this error a large part of his valuable work on 

 the Human Understanding. The child that opens its eyes to the light, 

 is prepared for the acquisition of ideas, by this merely, that it has 

 senses; that it is susceptible of impressions from the objects that sur- 

 round it. 



It is inaccurate, however, to compare, as some philosophers have done, 



* I ought to observe, that the terms thought and understanding are, in my opinion, 

 synonymous ; both are alike, an abridged expression of the whole of the operations of 

 the sensitive centre. Author's Note, 



