The main message of this passage is that even though we might feel like there is silence, there is always our thoughts that aren't quiet.
Explanation:
When Jack London explains the setting as " the lone and silent land," it shows that there is really nothing that could cause harm to the character. As London goes on in the passage, he begins to describe " the hunting cries..." and how "they sent surges of fear through the toiling dogs." This represents the thoughts of everyday people and the fear of the unknown. London then goes on to say " I wish they'd strike game somewheres, an' go away an' leave us alone." "They do get on the nerves horrible." These quotes represent the racing thoughts of the two characters, Bill and Henry, and how, even in the silence of the night, their thoughts are still heard loud and clear in their heads about the possible creatures that lurk in the dark.