But in the tropics,--the native land of the hammock,--not only the mysteries of the night, but the affairs of the day may be legitimately investigated from this aerial point of view. It is a fetish of belief in hot countries that every unacclimatized white man must, sooner or later, succumb to that sacred custom, the siesta. In the cool of the day he may work vigorously, but this hour of rest is indispensable. To a healthful person, living a reasonable life, the siesta is sheer luxury. However, in camp, when the sun nears the zenith and the hush which settles over the jungle proclaims that most of the wild creatures are resting, one may swing one's hammock in the very heart of this primitive forest and straightway be admitted into a new province, where rare and unsuspected experiences are open to the wayfarer. This is not the province of sleep or dreams, where all things are possible and preëminently reasonable; for one does not go through sundry hardships and all manner of self-denial, only to be blindfolded on the very threshold of his ambition. No naturalist of a temperament which begrudges every unused hour will, for a moment, think of sleep under such conditions. It is not true that the rest and quiet are necessary to cool the Northern blood for active work in the afternoon, but the eye and the brain can combine relaxation with keenest attention. In the northlands the difference in the temperature of the early dawn and high noon is so slight that the effect on birds and other creatures, as well as plants of all kinds, is not profound. But in the tropics a change takes place which is as pronounced as that brought about by day and night. Above all, the volume of sound becomes no more than a pianissimo melody; for the chorus of birds and insects dies away little by little with the increase of heat. There is something geometrical about this, something precise and fine in this working of a natural law--a law from which no living being is immune, for at length one unconsciously lies motionless, overcome by the warmth and this illusion of silence. The swaying of the hammock sets in motion a cool breeze, and lying at full length, one is admitted at high noon to a new domain which has no other portal but this. At this hour, the jungle shows few evidences of life, not a chirp of bird or song of insect, and no rustling of leaves in the heat which has descended so surely and so inevitably. But from hidden places and cool shadows come broken sounds and whisperings, which cover the gamut from insects to mammals and unite to make a drowsy and contented murmuring--a musical undertone of amity and goodwill. For pursuit and killing are at the lowest ebb, the stifling heat being the flag of truce in the world-wide struggle for life and food and mate--a struggle which halts for naught else, day or night.