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 sey- 
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 
1Darwin’s Voyage of the Beagle. 
