A race of sentient horselike creatures -- the Atheleni -- inhabits a distant planet. Separated into two different races, each fights the other in a constant battle for food. For though their mental capacity is developed to a staggering degree, these telepathic creatures have no concept of artificial devices. They have no appendages with which to manipulate their surroundings, having two hooves in front and a single hoof in the rear. But a member of their race has discovered something astounding. A different race on a distant island across a nearly impassable river has evolved appendages and has even managed to build crude tools. These Stone Age creatures, combining their manipulative skills with the awesome mental powers of the Atheleni, are beginning to make discoveries at an accelerated rate, each freeing the other from their respective natural prisons -- one mental, one physical.

Published in Science Fiction Quarterly (August 1951). Reprinted in:

• Expedition to Earth
• The Best of Arthur C. Clarke: 1937-1971
• Tales from Planet Earth
• The Oxford Book of Science Fiction Stories
• The Collected Works