What questions define Economics? To me, the most important problems that we have to tackle are: Why did the Industrial Revolution happen where it did, when it did, and why not elsewhere? and What caused the Great Depression? If Economics is the study of social behavior, especially in the marketplace, it would be hard to think of any event of comparable impact. These questions can be distilled to the more universally applicable "What are the causes of wealth?" and "What causes the economy to fall off the tracks?"
Macroeconomics has a lot to say about both of these, but its contributions to the first one seem unsatisfactory; the business cycle literature seems much more compelling than the growth literature. While the bumps that happen in modern economies is probably a much more poignant area of study right now, given the current state of the world, I find the first question much more interesting. Most of the non-class related economics reading has been about the Industrial Revolution, and why it happened.
I came into graduate school thinking that the change that enabled the IR was the growth of humanism - the belief of an individual that he or she can do something to improve his or her lot in life. Once that becomes the norm people are more willing to do little things differently; apply new technologies and methods to their work, come up with new ideas themselves, etc. The major inventions certainly helped, but as I mentioned last post a steam engine is useless if it is only a curiosity or a mental exercise on the part of its creator. I justified my belief by looking at how philosophy and theology had changed to some extent post-Aquinas. Obviously I can think of a hundred problems with this as the cause of the IR, one of which would be showing that a lot of people, rather than the select few clerisy thought this way; another would be showing that economic growth didn't encourage humanism rather than the other way around.
My primary source this year (as I'm sure no one will be surprised to learn) has been Deirdre McCloskey. I loved The Bourgeois Virtues (even though, I admit, she was long winded), though this seems like it lays some foundation rather than looking at the cause of economic growth. Her next book in the series, Bourgeois Dignity: Why Economics Can't Explain the Modern World, explicitly looks at and criticizes some current explanations, including Gregory Clark's work and Douglass North's. Her next-next book The Bourgeois Revaluation: How Innovation Became Virtuous is available in rough parts on her main page.
Right now I'm going through Douglass North's "The Rise of the Western World." We'll see what he convinces me of.