2 S IRRITATIVE MOTIONS. SECT. VII. 3. 2 . 



ted by irritation give us neither pleafure nor pain, we ceafe to 

 attend to them. Thus whilft I am walking through that grove 

 before my window, I do not run againft the trees or the benches, 

 though my thoughts are ftrenuoufly exerted on fome other ob- 

 ject. This leads us to a diftind knowledge of irritative ideas, 

 for the idea of the tree or bench which I avoid, exifts on my 

 retina, and induces by aflbciation the aftion of certain locomo- 

 tive mufcles ; though neither itfelf nor the adions of thofe muf- 

 cles engage my attention. 



Thus whilft we are converting on this fubjecT;, the tone, note, 

 and articulation of every individual word forms its correfpondent 

 irritative idea on the organ of hearing ; but we only attend to 

 the aflbciated ideas, that are attached by habit to thefe irritative 

 ones, and are fucceeded by fenfation ; thus when we read the 

 words " PRINTING-PRESS" we do not attend to the fhape, fize, 

 or exiftence of the letters which compofe thefe words, though 

 each of them excites a correfpondent irritative motion of our 

 organ of vifion, but they introduce by aflbciation our idea of the 

 moft ufeful of modern inventions ; the capacious refervoir of 

 human knowledge, whofe branching dreams diffufe fcienceSj 

 arts, and morality, through all nations and all ages. 



SECT. 



