Chugging along in my efforts to keep up wit my degree (M.A. History), I've been working my way through a pile of books on Ancient Greece for over a year now. Some of them are old favorites (Francois Hartog's Memories of Odysseus, The Cambridge Companion to Homer), some have been new works by favorite authors (Robin Lane Fox's Travelling Heroes in the Epic Age of Homer), and some have been completely new (Vassos Karageorghis' Early Cyprus). Then there's also that matter of learning to read Greek (we'll see how that goes). Anyhow, all this study has opened my eyes to things I ought to have picked up earlier, or that maybe I had but was too busy to put into words. Very few people are born researchers. It usually takes decades to produce a real historian, and there's no reason to suppose that I'm any different. In fact, the one admonition I received at Oxford that always stuck with me was "you need to take more time to think." So here's me thinking.
I've realized (probably a day late and a dollar short) that secondary sources, at least in the field of history, can be broken down into several categories:
1. Books About Books: These are works that seek to grapple with the primary sources (those writers writing closest to the event). In general, these works seek to extrapolate and organize information (both that which the author intended and that which he (or rarely, she) left unwittingly) and bring it to bear either on a historical question or on the question of how we ought to read the given text. For examples see: The Cambridge Companion to Homer.
2. Books About Cultures, People, and Events: While these books will make use of primary sources, their goal is broader than the work of any one ancient author. These are the books we generally think of when we think "History." Drawing from many different sources, and often relying heavily on archeology, they seek to tell us what past peoples, places, battles, etc. might have been like (the past as it essentially was, not as it actually was) or to grapple with issues raised by said reconstructions. For examples see: Early Greece by Oswyn Murray, or Salamis by Barry Strauss.
3. Books About Systems and Mentalities: Some works in the field of history aren't about any one particular person, battle, or culture, but are focused on a particular issue raised by the study of several different people, places, or cultures. These works often bring to bear the fruits of sociological, linguistic, and psychological studies to examine broader questions about the past. Often, they seek to reconstruct the mental world of a culture, or a group of cultures. They may seek to refine or correct work done by books in categories 1 and 2 (and thus I've given them their own number though we might elide them with 2). For examples see: Memories of Odysseus by Francois Hartog, or Traveling Heroes in the Epic Age of Homer by Robin Lane Fox.
4. Books About the Field of History: Books in this category focus on theory and method. They aren't focused on what happened in the past so much as how we are or ought to be going about our study of the past. Sometimes, these books are written for the instruction of new initiates into the field. Other times, they are written in response to some scholarly controversy or to advocate a new method or model. For examples see: Who Killed Homer? by Victor Davis Hanson, or Decoding Ancient History by Thomas and Wick.
Generally, in a course of study 2 should proceed 3. 4 and 1 can go together quite nicely as well as 1 and 3 (see Peter Hunt's Slaves, Warfare, and Ideology). Often, I think, 2 should proceed 1, and 1 should only be attempted after reading the primary source in question. Of course, I'm always going to push for the primacy of the primary sources, but I will confess that reading a type 2 book before plunging in to the primary sources can enrich your understanding of them and make the journey more fruitful by supplying a little context for what's seen along the way.
Well that's what I have so far. Let me know if you think I ought to add another category or abolish one for simplicity's sake, etc.