I INTRODUCTION 23 



Impressions change with the varying move- 

 ments of the mind, and we are led by a happy 

 illusion to believe that we receive from the ex- 

 ternal world that with which we have our- 

 selves invested it." 



Humboldt also singles out for especial praise 

 the following description given of Tahiti by 

 Darwin ^ : — 



" The land capable of cultivation is scarcely 

 in any part more than a fringe, of low alluvial 

 soil, accumulated round the base of mountains, 

 and protected from the waves of the sea by a 

 coral reef, which encircles at a distance the 

 entire line of coast. The reef is broken in sev- 

 eral parts so that ships can pass through, and 

 the lake of smooth water within, thus affords 

 a safe harbour, as well as a channel for the 

 native canoes. The low land which comes 

 down to the beach of coral sand is covered by 

 the most beautiful productions of the inter- 

 tropical regions. In the midst of bananas, 

 orange, cocoa-nut, and breadfruit trees, spots 

 are cleared where yams, sweet potatoes, sugar- 

 cane, and pine-apples are cultivated. Even 



1 Darwin's Voyage of the Beagle. 



