Slava Akhmechet suggests that reading five books on a topic can make you as close to well-informed as anything can. Reading just one book doesn’t cut it.

A single book is a pinhole view of the world set up by the author. You have no input into its contents, and therefore cannot change the orientation of this view. But you do choose the books you select. That means you can stitch together multiple pinhole views into a unique lens to examine the world— one that no one else will have unless they use the same list of books to stitch together the same lens.

I settled on clusters of five and almost never read a single book in isolation. Less than five feel lacking; more than five gets repetitive. Every cluster has a goal of the form “study X through Y”. Study American history through technological expansion, or study failure through one term presidents are just a few examples. I try to be creative and make Y unusual. For instance, everyone likes to read about presidents who are believed to be successful. A simple trick is to inverse it and read about unsuccessful ones instead. Or skip the presidents altogether, and read about vice presidents. It doesn’t matter what Y is because you’re trying to study X, and it’s more fun to make Y unusual.

This strategy is similar to Tyler Cowen’s, who also happens to read a lot, lot more (five to ten books a day seems rather excessive to me). From EconTalk’s podcast with Cowen:

I brought the books I’m reading now. So, here’s a book: It’s called Land, Politics and Nationalism: A Study of the Irish Land Question, by Philip Bull. He goes through Irish land debates in the 19th century. I read about two thirds of this book. It’s from the library. I’m going to read most of it again, but only after I’ve read other books about Irish land history. So, to reread it twice in a row makes no sense. To read it again 10 years from now for me makes no sense. But I like to read books in clusters; and overall, it’s a good book. Much of what Bull says will have much more meaning to me after I’ve read four or five other books on the 19th century Irish land question. That is how and why I’m going to reread, say, at least two thirds of this book.

It’s interesting that Cowen does not take notes. Cowen uses books to extract contexts - frameworks, models - and he has good enough memory to remember them. I hardly remember the books I read unless I write about them. I can only hope, like Emerson says, that the books have made me even if I don’t remember how.

Both Cowen and Russ Roberts insist that you don’t have finish books you have started if they don’t hold your interest. Life is short and all that. I have come around to that view lately, although I wish I had learnt that lesson much earlier. When you are younger you think you will live forever. At 30, you wake up one day and realize that your parents have grown smaller, look weaker and that you will eventually get to where they are. It put things in perspective, helps one prioritize. As much as I would have liked it, I doubt I would have learnt this lesson earlier.