Wilde's wit here operates on two levels—the surface joke about youthful arrogance, but deeper, a claim about *how knowledge actually works*. True learning requires acknowledging the vastness of what remains unknown, a humility that paradoxically grows harder to maintain as we accumulate years and credentials. Consider the experienced surgeon who still consults colleagues before an unusual case, versus the med student convinced he's grasped everything from his textbooks; the surgeon has earned the right to say "I don't know" precisely because he's lived long enough to meet his own limitations. Wilde suggests that wisdom isn't the endpoint of gathering facts—it's the ongoing practice of being surprised by the world.