Bradbury employs a reverential tone in the language he uses to describe the prehistoric jungle, presenting nature itself as a power that deserves the respect of humans, and as the Tyrannosaurus Rex emerges from the jungle, Bradbury’s vivid imagery conveys the beauty, strength, and fearsome presence of this now-extinct predator.

Against the backdrop of pristine and reverential nature imagery, the human characters in the story perform terrible deeds. Travis cautions Eckels to follow the rules of the Time Safari in order to protect the natural processes at work. Travis and Lesperance may initially appear to be stewards of nature, given their careful approach to time travel and their apparent awareness of the risks involved in traveling back to prehistoric times. In reality, however, the leaders of the safari contribute directly to a corrupt system that puts nature at risk by facilitating the trips in the first place. Their emphasis on following the rules stems not from some altruistic motive, but from their desire for their employer, Time Safari, Inc., to be allowed to continue to operate. Indeed, when he discovers Eckels has ventured off the Path, Travis's first thought is not for nature but for the company:

He ran off the Path. That ruins us! We'll forfeit! Thousands of dollars of insurance! We guarantee no one leaves the Path. He left it. Oh, the fool! I'll have to report to the government. They might revoke our license to travel. 

Travis even admits that Time Safari, Inc., has to pay bribes in order to carry on their work, perhaps because the ethical implications for nature and mankind are so serious.

When he finds himself in the prehistoric jungle, Eckels grows panicked and clumsy, and he inadvertently tests Travis’s theories about what happens when humans leave even a small mark on the past, proving that one single careless gesture can have terrible consequences. The crushed butterfly on the bottom of Eckels’s boots represents nature, while Eckels himself seems to represent all of mankind. Together, they illustrate the potential havoc humans can wreak by recklessly meddling with the balance of nature.