Feebleness of mans intellect. 147 



hundred-thousandth of a Centigrade degree change of 

 temperature, he can hardly detect a difference of an 

 entire degree; and whilst carbon and platinum maybe 

 heated to whiteness without material change, a rise 

 or fall of about five Fahrenheit degrees in his tem- 

 perature endangers his life. His mental and intel- 

 lectual powers are as limited as his senses ; he can 

 hardly reckon without making an error even a single 

 million, nor can he conceive an adequate idea of a 

 billion ; a million miles or a millionth of an inch are 

 each quite beyond his immediate perception ; an ex- 

 tremely minute circumstance also is capable of disturb- 

 ing and entirely diverting his train of thought. He 

 cannot create or destroy even a particle of dust, nor 

 form out of nothing a single idea. The velocity of 

 transmission of his nervous power, and the speed of 

 his execution of will, are also extremely slow in com- 

 parison with that of an electric current in a copper wire. 

 Every person is aware that he can only very slowly 

 receive and understand a new idea. His mental 

 advance is as tardy as his locomotion, a sixth part of 

 his life is spent in acquiring the merest rudiments of 

 universal knowledge. Whilst his reasoning power, 

 when applied to actual and truthfully stated experi- 

 ence, is truly " the great guide " of his life, it only 

 renders explicit what was already contained in that 

 experience ; for when he draws an inference, he 

 usually only states in one form of words, what he has 

 already implicitly included in the propositions ; and 

 if the inference contains more than this it is unwar- 



p P 



