This response is to the short science fiction story “A Sound of Thunder” by Ray Bradbury. A man named Eckels decides to go on a so-called “Time Safari,” on which one can hunt real dinosaurs by going into the past. Great caution is employed to avoid disturbing the past, and the dinosaurs that are killed are selected so that they would have died soon regardless. The hunt for the T-Rex goes awry, and Eckels ends up leaving the prescribed path and squashes a butterfly. They return to find their time subtly but significantly changed for the worse, leading the other safari members to despair and kill Eckels.
The story is the originator of the so-called “butterfly effect,” wherein a small change in the distant past may have massive historical implications given enough time. The writing is straightforward, and the twist ending is not challenging to guess given the information provided throughout the plot. It should be noted that the story contradicts itself to a degree, as the death of the dinosaur in a slightly different location at a somewhat different time could have similar implications. Nevertheless, its message is powerful and clearly delivered, and so it remains a classic and lends the name to a famous science fiction concept.