“Expiring knowledge catches more attention than it should, for two reasons. One, there’s a lot of it, eager to keep our short attention spans occupied. Two, we chase it down, anxious to squeeze insight out of it before it loses relevance. Permanent information is harder to notice because it’s buried in books rather than blasted in headlines. But its benefit is huge. It’s not just that permanent information never expires, letting you accumulate it. It also compounds over time, leveraging off what you’ve already learned.”