Alexander von Humboldt, Aspects of nature, in different lands and different climates… (1849)
“ At such times the larger animals seek shelter in the recesses of the forest, and the birds hide themselves under the thick foliage of the trees, or in the clefts of the rocks; but if, in this apparent entire stillness of nature, one listens for the faintest tones which an attentive ear can seize, there is perceived an all-pervading rustling sound, a humming and fluttering of insects close to the ground, and in the lower strata of the atmosphere. Every thing announces a world of organic activity and life. ”
