Teachers

They say “those who cannot do, teach”, but, on the flip side, when the expert (or prodigy) is unable to teach their field of expertise to someone, it may be due to the very thing that makes them the expert to begin with: they have assimilated the foundation to the point where they no longer need to think about it, and, therefore, are unable to decompose it into its original, teachable parts. You may experience this if you ever have to teach or write about your own expertise, and you may experience this is a more negative way if you ever have to learn from an expert that has not grappled with this beforehand. So we could say “those who cannot teach, do”, which sounds unfair, very much like the first quote.