To me, the most influential line in the chapter “Economy” is this: “Man is an animal who more than any other can adapt himself to all climates and circumstances” (located on page 60 in my copy of Walden). Thoreau shares this viewpoint after discussing baker’s yeast and how he has removed it from his diet. He claims he has “gladly omitted” using it ever since he “scalded” his yeast one day. Thoreau does share a very detailed account of his diet and the reasoning behind his dietary choices, and I think that is why the quote I mentioned above stood out to me so much. It is such a broad statement about humanity’s adaptability, and I am sure that Thoreau was not only thinking about adapting away from using yeast when he wrote that line. The statement seems to have much greater implications about how humans have effectively colonized the world and have now changed the climate (although Thoreau’s time period prevented him from witnessing the majority of that effect).
Stylistically, this passage of “Economy” is rich with detail and includes some imagery about the yeast bottle bursting in Thoreau’s pocket and disapproving housewives reacting to his omission of yeast. The language used is generally simple, but references to Christianity, Hinduism/India, and Arabia are also inserted into the text every few paragraphs. I am not sure if Thoreau has traveled to these regions, or has only studied them, but he seems to value making references to them. Perhaps the yeast in this passage is a sort of metaphor for human societal standards, and Thoreau choosing not to use yeast reflects the fact that he is not participating in society in the same way the majority of the villagers do.