SOURCES OF FALSE BELIEFS. 103 



sions. Anything which we cannot perceive by the aid of 

 our senses, we are apt to believe does not exist. There 

 are, however, whole multitudes of phenomena which con- 

 tinually exist or happen without our directly perceiving 

 them, because we do not possess senses suitable for the 

 purpose. Thus we are totally unable to perceive by 

 means of our senses an immense number of conditions 

 and changes, magnetic and other molecular phenomena, 

 which are continually existing or taking place in material 

 substances and in ourselves. In consequence also of 

 the finite extent of our senses the effects produced upon 

 us by the circumstances of the external world, or by 

 the physical and chemical changes within us, are not 

 proportionate to the real magnitude of the phenomena ; 

 the magnitude of extremely great things we cannot ade- 

 quately appreciate, and exceedingly small things we 

 cannot at all perceive ; and even of the multitudes of 

 perceptible things around us we can only observe at once 

 a very small proportion. We are at the same time the 

 nearly helpless creatures of nervous impressions, and are 

 largely unable to prevent ourselves being impressed by 

 those circumstances which we directly perceive. Whilst a 

 few things thus compel us to feel their presence, a multi- 

 tude of others do not affect our consciousness at all, and 

 our immediate experience thus misleads us. The sensa- 

 tions and impressions also which we receive from one phe- 

 nomenon are almost invariably mixed up with those we 

 almost simultaneously receive from others and from our 

 physical frame, and we can but rarely exclude all but the 

 one we are observing. Also, whilst myriads of things and 

 actions exist simultaneously around and within us, we are 

 quite unable to think of more than a few (some persons 

 say, five or six) at a time ; even a single thought requires 

 time, and it would occupy us several years to think of each 



