All truth, in the long run, is only common sense clarified.

Difficult ideas often end up sounding obvious once they are properly worded, and that is no sign they were easy. The clarifying is the work: stripping out the confusion, the false distinctions, the words that sounded impressive and meant nothing. What remains looks like something you already knew, which is exactly why it lands.

Use that as a test on anything you are trying to understand. If you cannot state it plainly to somebody outside the field, you probably have not finished. And be suspicious of explanations that stay complicated no matter how long you look at them.