To refuse to understand things.
cast pearls before swine
To give things of value to those who will not understand or appreciate…
rocket scientist
One qualified to handle or understand things which are very complex or…
slow study
One who takes a long time to learn or understand things; a slow learne…
quick on the uptake
Able to readily understand things; aware and intelligent.
know one's own mind
To clearly understand one's own feelings, intentions, preferences, etc…