ITS VALUE AND LIMITS. 77 



most observant life cannot exhaust. Exhaust ! the 

 use of it is the very reverse ; for we absolutely mul- 

 tiply it in the same proportion as we use it ; and the 

 hand which can do the most is the readiest in the 

 successful performance of any thing new. 



But still, exquisite as is the discrimination of the 

 hand, it can take note only of that which has the most 

 obvious properties of matter. It has, indeed, a sen- 

 sibility to heat and cold, but that is vague and variable, 

 inasmuch as it is only the difference between the 

 touching body and the substance touched, and the 

 body gives no information as to its own temperature, 

 and but a shadowy one of the relative temperatures 

 of other things. The real offices of the hand, or 

 rather of that muscular feeling of which the hand is 

 one of the most perfect instances, are, acting as a 

 balance to measure pressure and resistance, and as 

 a line to measure space ; and though its sensibility 

 in both these respects is exquisite almost to infinitude, 

 we can collect the little differences until their sum 

 is of such magnitude as that we can recognise and 

 cross-examine it by the eye, so as to make the one 

 organ of observation establish the truth of the other. 



But exquisitely fine as the discrimination of the 

 hand can be rendered, arm's length bounds the range 

 of its knowledge; and muscular power can take 

 heed of nothing save that which resists it by con- 

 tact ; so that if our observation were limited to the 

 hand or the muscular feeling, it would be less excur- 

 sive than that which we obtain by smelling which 

 does not define or even point out the situation of its 

 object at all. Thus, though we may grope our way 

 very minutely and very nicely to the details of na- 

 ture in the dark, we should never be able to group 

 them, or to comprehend the beauty or grandeur of 

 nature, if we had not powers of observation scarcely 

 less limited in extent than excursions of mind itself. 



Now we have two remaining senses, the one of 

 which more immediately enables us to learn from 

 G2 



