Simple can be harder than complex: You have to work hard to get your thinking clean to make it simple. But it's worth it in the end because once you get there, you can move mountains.
Reflection
There’s another version of this thought that I like. I’m also not sure of the quote but it’s something like, “I’m sorry I wrote you such a long letter, I didn’t have time to write a short one.”

What I think is most useful in this is the power of simplicity. Something simple is easier to grasp and to convey. The true challenge is moving toward simplicity without losing the power of the depth and nuance. In my mind, there’s a sequence of utility and power and it goes simple -> complex -> simple. It’s easy for something to be simplistic and wrong. Adding complexity can add correctness. And this is where a lot of people stop. But the real power, the power to “move mountains” is when you take the next step into simple again.