It’s nature, like the weather in the extract, such as ‘bitterly hard weather’ and ‘the Earth was like iron’. Hope this helps!
Answer: The last word of Keesh was "It is not for a boy to know about witches, and I know nothing about witches. I only have means whereby I may kill an ice-bear with ease, that's all. It would be headcraft, not witchcraft".
In "The Story of Keesh" by Jack London, the people of the tribe did not believe that Keesh had hunt a large polar bear by himself, so they accused him and his mother of witchcraft. It required dignity and manhood for him to defend himself and speak against the elder hunters who disliked him.
You need to show the sentence first
It's either internal or psychological