As we’ve written about before, one of the most surprising parts of Seneca’s writing is how that avowed Stoic quotes Epicurus, the founder of Epicureanism. Even Seneca knew this was strange as each time he did so in his famous Letters, he felt obliged to preface or explain why he was so familiar with the teachings of a rival school.

His best answer appears in Letter II, On Discursiveness in Reading, and it works as a prompt for all of us in our own reading habits. The reason he was so familiar with Epicurus, Seneca wrote, was not because he was deserting the writings of the Stoics, but because he was reading like a spy in the enemy’s camp. That is, he was deliberately reading and immersing himself into the thinking and the strategies of those he disagreed with. To see if there was anything he could learn and, of course, to bolster his own defenses.

It’s very easy, especially in today’s social media and algorithmic world, to become caught in a feedback loop of your own viewpoints. You read an article about one topic, and suddenly, all you see are more and more pieces about that same topic. You watch a video from a partisan on one side of the spectrum and now that’s all you see. The idea that there are other cogent, good-faith arguments on the other side—well that becomes more and more remote. Even falling down the rabbit hole of Stoicism can have a similar effect. There is so much to read, so much interesting stuff, that the idea of putting it aside to research Buddhism or Christianity or even reading great novels seems crazy.

But it isn’t. You have to take the time to study and look at things that are different than what comes easy or comfortably. You have to be open to hearing things you disagree with too. Remember Epictetus’s line that you can’t learn what you think you already know. That’s why it’s important to read and study like a spy.

Go into the enemy’s camp. Open your eyes and mind to what they’re doing. Use what you learn.