I'd like to add another citation from Nicolas Boileau (17th century) that my father used to tell me frequently: "Whatever is well conceived is clearly said, And the words to say it flow with ease." ("Ce que l'on conçoit bien s'énonce clairement, et les mots pour le dire arrivent aisément.")
I think about it often especially when someone tries to explain something and it seems hard, very often this means it's also hard for them.
Being able to explain something (clearly) to someone else is a great way to measure your own understanding. The more complete your understanding, the better your ability to communicate it.
I think about it often especially when someone tries to explain something and it seems hard, very often this means it's also hard for them.