After spending about fifteen years on the island, Crusoe found a man's naked footprint, and he was sorely beset by apprehensions, which kept him awake many nights. He considered many possibilities to account for the footprint and he began to take extra precautions against a possible intruder. Sometime later, Crusoe was horrified to find human bones scattered about the shore, evidently the remains of a savage feast. He was plagued again with new fears. He explored the nature of cannibalism and debated his right to interfere with the customs of another race.
Crusoe was cautious for several years, but encountered nothing more to alarm him. He found a cave, which he used as a storage room, and in December of the same year, he spied cannibals sitting around a campfire. He did not see them again for quite some time.
Later, Crusoe saw a ship in distress, but everyone was already drowned on the ship and Crusoe remained companionless. However, he was able to take many provisions from this newly wrecked ship. Sometime later, cannibals landed on the island and a victim escaped. Crusoe saved his life, named him Friday, and taught him English. Friday soon became Crusoe's humble and devoted slave.