What do the goats symbolize?

[John]

When Crusoe first pitches up on the Island he sustains himself by shooting goats, the only meat he feels is edible. After a while he starts to breed them and keep them in captivity, and he feels close to them, and returns often to them as key components of his 'kingdom.' When the natives first come on the Island in their canoes and indeed feed on their own captives, Crusoe has a vision of a footprint and then sees a pair of eyes looking at him from one of his caves, which he thinks may be one of the 'savages' but which are in fact, the eyes of Billy Goat. Is this a moment of comic relief in the book, or is he entering to a form of madness, so that eventually he feels justified to go and kill some of the savages, even though he has no grudge against them personally?