A topic sentence is a sentence that introduces a paragraph by presenting the one topic that will be the focus of that paragraph. You introduce your topic in the introduction, explain various parts of the topic in the body, and revisit the topic in the conclusion. Therefore, a good essay will have a topic sentence in all of the above.
Well I would say that one of the central themes in Ernest Shackleton's South can be analyzing the complexity of the fight between the individuals and the society along with its "norms", in a world where nature is somewhat relentless towards humans. Hope this helped.
