1+1=2 is the whole shebang. nothing more to see, eebida eebida eebida that's all folks.
e=mc2 isn't nearly the whole shebang. But it is the door you enter through.
Sometimes things are simple, sometimes they're simply accessible. Often we're too close to be able to tell the difference, it's an important one though.
Of course Einstein himself said "If your idea can't be explained on the back of a napkin, you haven't thought it through."
Here's a very simple idea though: