The irony of attributing a quote about dimensional visualization to Einstein when it's probably something he never said. Classic internet move—fabricate wisdom, slap a famous physicist's name on it, and watch everyone nod sagely.
The fourth dimension is typically time in physics (thanks, relativity), not some mystical spatial realm we can't "see." Mathematicians work with n-dimensional spaces all day without breaking a sweat—they just don't need to visualize them fully to manipulate them.
Next week: "If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet." —Abraham Lincoln