All because of his fear at seeing a single footprint, Robinson worked tirelessly in constructing his new goat pen, building a strong fence around it. He says that he lived under anxious fear from the footprint for two years. He prayed to God only out of great distress, fearing that he would be taken by cannibals or savages, and says that he thus did not pray properly with "a temper of peace, thankfulness, love, and affection."
Robinson continues to be driven by fear at the unknown person who left the footprint. Looking back as narrator, he realizes how his fear caused him to waver in his devotion to God and stop praying properly.
Robinson then explored the island for another place to build a small livestock pen, and while walking up a hill saw a boat out at sea. When he came down the hill to the shore, he saw skulls and human bones scattered all around and a fire pit. He was so horrified and disgusted by this and by the thought of cannibalism, that he vomited.
This is Robinson's first encounter with any evidence of cannibalistic behavior among "savages." He reacts with a mixture of fear and disgust.
Robinson hurried back home and thanked God that he had not been born among such savages as those who had left the remains of their victims on the shore. Back safe in his "castle," Robinson reasoned that he had been on the island for eighteen years without encountering any savages in his part of the island, and so he would likely be able to continue living here without encountering them.
The sight of the human remains gives Robinson another reason to be thankful to God—for being born in a Christian society where cannibalism does not occur. Robinson hopes that he can continue to live a solitary, secluded life on his island.
Nonetheless, Robinson remained frightened for the next two years, during which time he never ventured beyond his "castle," his "country house," and his new goat enclosure. He gradually became more at ease again and, amid such danger, was newly appreciative of the fact that his life could have turned out to be much worse.
Scared of encountering a savage, Robinson isolates himself even further on his already isolated island, not venturing outside of his dwellings. Still, throughout all of this, he comes to a greater appreciation for his life, since it could have been much worse.
Robinson harbored thoughts of attacking the cannibal savages when they next landed on the island and of rescuing their victims. He planned to hide and ambush them with his guns and started going to a tall hill every day to look for any ships coming to the island.
Robinson's fear of the cannibals leads to thoughts of violence, as he plans to attack the next group of them he sees.
The more he thought about this, though, the more Robinson thought he had no right to intervene in the savages' lives. He thought that God had seen it fit that they should live in this way and he reasoned that from the savages' perspective it was not unlawful or wrong to kill and eat prisoners.
Robinson concluded that he had no right to kill the savages and thought of how this would be similar to the "conduct of the Spaniards in all their barbarities practised in America," describing how the Spanish killed millions of innocent people. Moreover, he realized that it was also not practical to attack the savages, because their comrades might come to avenge them by killing him after.
Robinson concludes that he should not attack the "savages," and distances himself from the cruel behavior of Spanish colonists (though Robinson himself has had no problems with profiting from the enslavement of Africans).
Robinson considered the savages to be innocent "as to him," because they had not done anything to him. He said that it was up to God to judge their crimes against each other. He thanked God for allowing him to come to this realization before making the mistake of killing any innocent men and prayed that he would continue to be safe from any "barbarians."
Robinson's relative tolerance toward the "savages" derives from his trust and faith in God, as he realizes that he himself should not take it into his hands to judge others and should instead leave such judgment to God.