It's what you learn after you know it all that's important.

The line warns against the complacency that comes with thinking one has mastered a subject. “After you know it all” points to the moment when confidence hardens into certainty—often the point at which learning stops. The quote argues that the most valuable growth happens beyond that threshold: in revising assumptions, noticing exceptions, and remaining teachable. It also implies an ethical dimension to knowledge—humility and openness are not optional add-ons but essential to continued competence. In practical terms, it praises lifelong learning and the capacity to be surprised, suggesting that expertise is proven not by having final answers but by continuing to learn when it feels unnecessary.