INTRODUCTION. 



IMAGINE that you have been living in the depth of a narrow 

 valley; that your view has been limited for years by the 

 slopes of the surrounding hills; that you have never seen 

 anything but green fields. Imagine next that, having 

 climbed to the summit of the nearest slope, you suddenly 

 behold an extensive horizon all around ; after the monotonous 

 valley, you wonder with delight at the magnificent prospect 

 displayed far and wide ; you count forests, rivers, lakes, 

 villages, and cities. Charmed with the novelties afforded by 

 so short a journey, you next ascend an elevated peak whence 

 the prospect may be extended far away, and once there, you 

 are struck with a sight infinitely grander : you behold on the 

 one side ranges of mountains eternally covered with snow 

 and lost in the clouds, whilst on the other side you behold 

 the blue and boundless ocean, whose horizon melts with the 

 azure sky. At this undreamt-of display you are speechless 

 with emotion. You feel you are contemplating a divine 

 work. 



The valley pictures the elementary knowledge acquired 

 during early youth. In that condition you can no more 



