Nature is the dominant environment for the Sioux. They calculate time according to events in nature: Months are named "the Moon of Popping Cherries," for example, or "the Moon when the Ponies Get Fat." Black Elk defines the state of goodness as that time when "the two-leggeds and the four-leggeds lived together like relatives"; now, he says, the whites "have made little islands for us and other little islands for the four-leggeds, and always these little islands are becoming smaller, for around them surges the gnawing flood of the Wasichu [white]; and it is dirty with lies and greed." He thus sees himself and his tribe as creatures of nature and harmony with nature as the ideal state — a state that is in opposition to white civilization.
The traditional Sioux way of life created interdependence between man and nature. Respect for the cycle of the seasons and animal life was necessary in order to secure food, clothing, and shelter. When the Indians lived in cooperation with nature, those necessities were available to them — available in such abundance, in fact, that their very existence seemed proof of the care of the Great Spirit. When the westward expansion of the whites destroyed that interdependence, it violated the Sioux's perception of the sacred as well as their way of life.
Respect for animals is a major feature of Sioux culture throughout Black Elk Speaks. The bison herd, for example, is central to the Sioux way of life; its existence is incorporated into ritualized hunting practices and feasting, and bison are killed with economy: Nothing is wasted, Black Elk says, in contrast to their arbitrary slaughter for sport by whites. The horses, which were so important to the Sioux for warring and hunting, are cared for and guarded carefully. They become sacred animals in Black Elk's vision, which he later enacts as the "horse dance." Black Elk's vision sensitizes him to animals; he can hardly bear to hunt after having the vision, and he feels a special kinship with the eagle after being given the power name Eagle Wing Stretches. In a small-but-touching episode, during the Canadian exile of the Oglala, Black Elk and the men he is with hear porcupines crying in the cold and do not harm them as they seek the warmth of their shelter.
Not only animals reflect the Sioux's relationship with nature. Voices of thunder and flying men in Black Elk's vision take him through the sky to a tepee made of clouds with a rainbow for a door. Ever after, for him, the sound of thunder will evoke the world of that vision, and he will look forward to rain as a visit from the spirit world. Black Elk describes spring several times as that time when "the grass shows its tender faces," so that it, too, is personified and a relative of human beings. The rain falling softly at the end of Black Elk Speaks is a validation of Black Elk's belief.