Recently Keith Nerdin asked me on Twitter what I mean by saying that I "work through" an author, as I am doing now with both Nietzsche and Thoreau. Because I found it difficult to capture the entire process in 140 characters, here's a longer treatment of the subject.
As part of my lifelong philosophy project, I'm attempting to distill the wisdom of six thinkers in as brief a compass as possible. For me, this requires several phases:
Read everything the author has ever written, at least once and preferably twice if I have the time. As I read, I mark up passages and phrases and even mere words of interest, usually with a red pen. (Yes, this is a bit sacreligious since I love books!)
Don't revisit the author for a while, so that the ideas can seep into my subconscious.
Read all of the marked-up sections again, preferably in the order in which they were written. As I do so, usually I will find some themes I can build upon. (With Rand it was thought, choice, action, and feeling as fundamental human capacities; with Epicurus it was various dyads of misperception and fear vs. dyads of clear thinking and joyful action.) To help me organize the material, I might make some marginal notes or letterings on the pages of the books about the themes I've found, perhaps keep separate lists of passages categorized by theme, etc.
Here again I will let the ideas lie fallow for a time. At this stage I might also read some of the secondary literature (e.g., I did read a few books and scholarly articles about Epicurus at one point), although I try not to overdo it because I find that I can get lost in other people's interpretations (this is especially true where vast hordes of scholars have labored over the primary material, as with Aristotle and Nietzsche). Since I'm writing each movement of this "happiness suite" in a different genre (essay, dialogue, poetry, commentary, etc.), I might also read in or about the genre I'm considering.
Then and only then do I start to write (although during the previous phases I might have made some jottings or outlines here and there). In a way, this is the easy part, because I've already absorbed the thinker's philosophy and have applied it a bit in my own life along the way. Thus the writing might simply grow organically out of the soil I've already cultivated.
After letting what I've written lie still again for a few weeks or months, I'll then polish off the rough edges and call it done. Because I tend to be mainly happy with what I write the first time around, typically I don't make major revisions at this point.
Naturally there are variations. With Rand, I had read all of her books once or twice or more as a teenager; thus when I decided to explore a theme from The Fountainhead (which I'd read nine or ten times before college!), re-reading it once and marking it up along the way was enough to give me plenty of material that I could weave into The Tao of Roark. With Epicurus, I had read the existing translations but I didn't like them; so, inspired by my friend Manuel, I decided to translate his words afresh from Greek into English, which enabled me to know his thoughts much more deeply than if I had merely marked up someone else's rendering. With Nietzsche, I had read most of his works back in college or soon thereafter, and I have recently completed the task of re-reading them in chronological order (there are a lot of red markings in my copies, waiting to be revisited). With Thoreau, I've read Walden a few times, and I've dipped into a few of his essays as well as selections from his journals, but it's only of late that I've become systematic about absorbing what he had to say (so far the essays and poems, soon the longer books, then the journal).
Although I'm not yet sure about the key notes that I hope to strike in my books on Nietzsche and Thoreau, the emphasis as always will be on practical wisdom, not theoretical elegance or doctrinal purity. I care about ideas as they apply to life, not as ends in themselves.
That said, I'm starting to perceive the dim outlines of an intriguing theme for the book on Thoreau (which I aim to finish before the Thoreau bicentennial on July 12th, 2017). I'll post on that topic as soon as the thesis becomes a bit more clear in my own mind.