The Story Behind the Email
The email dates to November 2003, when Mattis — then a Marine general with the 1st Marine Division — was preparing to return to Iraq. A military colleague had remarked, in effect, that operational demands left no time for reading. Mattis disagreed forcefully, and his reply was forwarded, posted, and eventually went viral years later as a fixture of professional military education. What gives the email its authority is its source: this was not a scholar lecturing from a campus but a combat commander writing from the field, arguing that reading had directly made him more effective in war. That credibility is why the message has been reproduced thousands of times and is taught to officers to this day.
What the Email Actually Says
The core of the argument is a contrast between two ways of learning. "The problem with being too busy to read," Mattis wrote, "is that you learn by experience (or by your men's experience), i.e. the hard way. By reading, you learn through others' experiences, generally a better way to do business, especially in our line of work where the consequences of incompetence are so final for young men." He went on to insist that the past is not obsolete: "Alexander the Great would not be in the least bit perplexed by the enemy that we face right now in Iraq," because warfare rests on fundamentals that have held for thousands of years. He then did what a good reader does — he pointed to specific titles, recommending Field Marshal Slim's account of his campaigns, Liddell Hart on Sherman, and histories of earlier fighting in Afghanistan, so the answers could be found rather than relearned at cost.
The "Functionally Illiterate" Line
The email is almost always quoted alongside the sharper line Mattis later put in print. In his 2019 memoir "Call Sign Chaos," he wrote: "If you haven't read hundreds of books, you are functionally illiterate, and you will be incompetent, because your personal experiences alone aren't broad enough to sustain you." The two statements make the same case at different volumes. The email explains the mechanism — reading borrows others' experience cheaply; the memoir line delivers the verdict — that skipping it leaves you incompetent. "Functionally illiterate" is the provocation: Mattis is not questioning whether you can decode words on a page, but whether you have read enough to draw on more than your own narrow life when the stakes are high.
Why the Argument Holds Beyond the Military
Mattis's logic is not specific to war. Strip out the battlefield and the structure remains: any consequential decision you face has almost certainly been faced before, and the record of how others handled it — what worked, what failed, and why — is sitting on a shelf. Learning it firsthand means paying tuition in mistakes; learning it from a book means inheriting the lesson for the price of reading. For a surgeon, an executive, an engineer, or a parent, the same calculus applies. This is why Mattis frames a refusal to read as close to "dereliction of duty" whenever a leader's choices affect others: it amounts to choosing the costly path to knowledge when a cheaper, faster one was available.
How to Apply Mattis's Reading Argument
Turning the email into a habit is straightforward. First, accept the premise: your own experience is a small dataset, and reading is how you enlarge it. Second, read toward the decisions you actually face — Mattis read specific campaigns because he expected to fight; choose books that address your real problems. Third, read for transfer, mining each book for the decision and its consequence rather than for trivia. Fourth, build a backlog before you need it, because the worst time to start learning a situation is while you are in it — the entire point of reading ahead is to never be "caught flat-footed." The constraint, for most people, is not access to books but the time and discipline to get through them.