What is the theme in Osborne Russell's Journal of a Trapper: Edited from the Original' by Osborne Russell?

Surviving and exploring the wilderness is the main theme of the book. Osborne Russell is employed as a trapper for the Columbia River Company and later is an independent trapper. This is how he earns his living, but he also enjoys exploring the Oregon Territory as part of the West. In his careful observations in his Journal, Russell shows his acute interest in the phenomena of the Northern Rocky Mountains region.