If you can't explain it simply, you don't understand it well enough.
The real bite here isn't about dumbing things down—it's that simplicity demands *mastery*, not surrender. Einstein was pointing to a common pretense: we often mistake jargon and complexity for genuine comprehension, when in fact a mind that truly grasps something can strip away the scaffolding of technical language. Watch a surgeon explain her work to a patient's worried child, then listen to a second-rate academic discussing their own research at a conference, and you'll see the difference immediately—one understands, the other merely memorizes. The person who folds under pressure to explain clearly has simply exposed where their knowledge actually ends.
“It is the mark of an educated mind to be able to entertain a thought without accepting it.”
Aristotle“Nature does not hurry, yet everything is accomplished.”
Lao Tzu“It is not that we have a short time to live, but that we waste a great deal of it.”
Seneca“People think focus means saying yes to the thing you've got to focus on. But that's not what it mean...”
Steve Jobs