At the beginning of the story, Rainsford's attitude is fairly cold toward the animals that he hunts.
Rainsford loves hunting, and he feels no sympathy for the animals that he hunts and kills. While Rainsford and Whitney are both on the boat, Whitney states that he believes that the jaguars that they are about to hunt have feelings. Rainsford dismisses the idea as nonsense, but Whitney persists that at the very least the animals must know fear.
"Even so, I rather think they understand one thing -- fear. The fear of pain and the fear of death."
Rainsford again responds by saying that the concept of animals having feelings is nonsense.
"Nonsense," laughed Rainsford. "This hot weather is making you soft, Whitney. Be a realist. The world is made up of two classes--the hunters and the huntees. Luckily, you and I are hunters."
Rainsford, as a hunter, doesn't even consider how his actions might make his prey feel. But once Rainsford becomes Zaroff's prey, Rainsford realizes exactly how all of the animals that he previously hunted most likely felt.