394 FALLACIES. 



almost every one had the opportunity of observing. 

 " A vague and loose mode of looking at facts very 

 easily observable, left men for a long time under the 

 belief that a body ten times as heavy as another falls 

 ten times as fast; that objects immersed in water are 

 always magnified, without regard to the form of the 

 surface; that the magnet exerts an irresistible force; 

 that crystal is always found associated with ice ; and 

 the like. These and many others are examples how 

 blind and careless man can be, even in observation of 

 the plainest and commonest appearances; and they 

 show us that the mere faculties of perception, although 

 constantly exercised upon innumerable objects, may 

 long fail in leading to any exact knowledge." 



The influence of a preconceived theory is well 

 exemplified in the superstitions of barbarians respecting 

 the virtues of medicaments, and of charms. The 

 negroes, among whom coral, as of old among ourselves, 

 is worn as an amulet, affirm, according to Dr. Paris *, 

 that its colour "is always affected by the state of 

 health of the wearer, it becoming paler in disease." 

 On a matter open to universal observation, a general 

 proposition which has not the smallest vestige of 

 truth, is received as a result of experience; the pre- 

 conceived opinion preventing all observation of such 

 instances as do not accord with it. 



4. For illustration of the first species of non- 

 observation, that of Instances, what has now been 

 stated may suffice. But there may also be non- 

 observation of some material circumstances, in in- 

 stances which have not been altogether overlooked 

 nay, which may be the very instances upon which 



* Pliarmacologia) p. 21. 



