POPULAR FALLACIES. 



These fallacies arise partly from mistaking tlie true character 

 and functions of the organs of sense. These organs were never 

 designed by their Maker to be the instruments of scientific 

 inquiry. If they had been so constructed, they would most pro- 

 bably have been unfit for the ordinary purposes of life. It is 

 observed somewhere, by Locke, we believe, that an eye adapted 

 to perceive the constituent atoms of the metal which forms the 

 hands of a clock might be, from the very nature of its structure, 

 incapable of informing its owner of the hour of the day indicated 

 by the same hands ; and it may be added, that a pair of telescopic 

 eyes, which would discover the population of a distant planet, 

 would ill requite the observer for the loss of that ruder power ot 

 vision necessary to guide his stops through the city he inhabits, 

 and to recognise the friends which surround him. The com- 

 parison of instruments adapted for the use of commerce and 

 domestic economy, and those designed for domestic purposes, 

 furnishes a not less appropriate illustration of the same fact. 

 The highly delicate balance used by the philosopher in his 

 inquiries respecting the relative weights and proportions of the 

 constituent elements of bodies, would, by reason of its very 

 perfection and sensibility, be utterly useless in the hands of the 

 merchant or the housewife. Each class of instruments, has, 

 however, its peculiar uses ; and is adapted to give indications 

 with that degree of accuracy which is necessary and sufficient 

 for the purpose to which it is applied. 



2. Of all the organs, that which would seem to be most exact 

 -and unerring in its indications is the eye ; and, although in a 

 certain sense this is true, yet there are no impressions which 

 more imperiously require the exercise of the judgment to adjust 

 and rectify them than those of vision. By this sense we receive 

 the perception, subject, however, to many qualifying conditions, 

 -of form, magnitude, brightness, and colour. There is not one of 

 these qualities, however, which is not frequently mistaken or 

 wrongly estimated. 



3. Every one, for example, is familiar with the appearance of 

 the sun and moon when rising and setting. The apparently large 

 orb which they present to the senses is an object of familiar 

 notice. Is not every one impressed with a conviction that the 

 apparent magnitude of the sun when it rises, glowing with a 

 redness acquired from the depth of air through which its rays 

 then pass, is much greater than the apparent magnitude of the 

 same object at noonday 1 and is not the same impression 

 admitted with respect to the rising or setting full moon, com- 

 pared with the same object seen on the meridian ? Yet nothing 

 is more easy than to prove, as a matter of fact, that these 



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