If you want to dig into Thoreau, then the book Thoreau: The Quest and the Classics (Yale University Press, 1951) by Ethel Seybold (Associate Professor of English at Illinois College) might help. I have not read it, so I do not yet know it’s content. I found it while digging into Walden while I was helping a student write a long essay on the book.
Optimal thought and optimal fitness through reason, logic, science, passion, and wisdom.