He felt the story was "perfectly simple" and didn't need any additional information to help the audience figure things out.
But this sort of thing usually turns out to have some perfectly simple explanation.
There had to be a perfectly simple explanation to all this - if only she could think what it was.
There is a perfectly simple solution to much of this.
I give you a perfectly simple case to work on.
But there was a perfectly simple explanation, if he'd only realized it.
Life was perfectly simple and easy, I felt, if one took it the right way.
With a perfectly simple bit of apparatus the whole thing could be arranged.
The answer is perfectly simple, once you stop to think about it.
"Trying to do things the hard way when we have perfectly simple everyday magic available."