If your class has also read Socrates, you might consider these famous words of Thoreau in the context of the ancient philosopher. Socrates advised that "the unexamined life is not worth living." Living "deliberately" necessitates some examination, if for nothing else to eliminate some of the surface on which we glide throughout our day. "Deliberately" involves making choices as to what we want to do and what we don't and then acting accordingly. It involves an active engagement with even the most mundane of tasks, and this in turn involves a sense of time as lingering. Modernism is all about speed, but in living deliberately one would refuse to rush. It involves "to be," preferring the process of life rather than the final product (what we produceby) of it.
This quotation from Thoreau's great work both pleases and frustrates me. On the literal meaning, it means just what he says: he went into isolation, living in nature, for purposes of philosophical deliberation. Like a monk living alone, he lived in the woods to get clear in his own mind and soul. The result was lovely.
I find it frustrating, though, because it leaves out the larger human society, and how it formed his desire for this isolation.