In his classic How to Read a Book, Mortimer Adler, citing Francis Bacon, tells us that “some books are to be tasted, others to be swallowed, and some few to be chewed and digested.” Yes, but which books and in what order?

Of the making of books there is — fortuitously — no end. It gives witness to our distinctive human persistence in thinking. There are a good many lists of “must read” books, and some lists purport to be a canon of Western literature. The aim of such canons is sometimes pedagogical and sometimes political.

Of late, having read more books than I can remember, I find myself wondering whether to read this or that book. And if I decide to read a particular volume, the next question is when to read it. Supposing that Shakespeare’s plays merit as much study as a book, I recall that my first academic dean often remarked that he was saving King Lear for his retirement years.

To be sure, the “whether” and “when” of reading a book depends on the reader and life’s endless variables. Still, there is a philosophical framework that can help structure our choices. How so? Because it is a framework of every human action.

Drawing on Plato and Aristotle, Aquinas teaches us that every human action has both a transitive and an intransitive dimension. What does this mean? Think of the distinction between a transitive and intransitive verb. A transitive verb requires a direct object. For example, Babe Ruth hits the ball. An intransitive verb does not. Example: I sleep through grammar lessons.

Karol Wojtyla (St. John Paul II) emphasized the ethical significance, for the agent, of the intransitive dimension of an act. Suppose for another example, I am an internet bully. Yes, I harm my targets. But I especially harm myself in that I become a bully. All things considered, it is better to suffer evil than to become evil.

Back now to whether and when to read a particular book. “To read” is an action. But notice that when I read a book, I have a minimal effect on the book, though my annotating the margins lowers its resale value. But my reading the book, depending on its content, can have a great effect on me — and the same is true for others who read the book. Libraries and publishing houses are part of our cultural wealth!

So, whether I should read “the next book on my list” largely depends on how that book will affect the person I am. The same is true for deciding when to read a book from my list. The plot thickens, and the opportunities become even richer, when I read more than one book at a time. Here variety comes into play. I’ll wager that I can become a better philosopher, a role central to my vocation, if I read a mystery by Josephine Tey in tandem with Aristotle’s Rhetoric, a book that’s been on my list for far too long.

And what about old favorites? Perhaps the next book I should read is one that I’ve already read. So it has been, of late, in my rereading Myles Connolly’s Mr. Blue. On my first read through, I had no idea that it was a counter to F. Scott Fitzgerald’s The Great Gatsby. On my first reading of Walter M. Miller, Jr.’s Canticle for Leibowitz, it didn’t dawn on me that science fiction could illustrate the eschatological significance or original sin. I’m currently rereading, after 60 years, José María Gironella’s The Cypresses Believe in God. This time I’m getting a lesson on the cyclical character of political hysteria.

Mortimer Adler, in his autobiography, offers us a final insight on books to read and recommend. A real student has a zeal for knowledge and the wisdom to which it can lead. But the fortunate student, and Adler considered himself one, also benefits from happy circumstances: meeting the right friends, having the right teachers, and reading the right books at the right time. Have we benefited from such circumstances? Probably. A resolution: Let’s do our share to see that others profit from them as well.