thru sadness we learn something

"The best thing for being sad is to learn something. That is the only thing
that never fails. You may grow old and trembling in your anatomies, you
may lie awake at night listening to the disorder of your veins, you may
miss your only love, you may see the world about you devastated by evil
lunatics, or know your honour trampled in the sewers of baser minds.
There is only one thing for it then — to learn. Learn why the world wags
and what wags it. That is the only thing which the mind can never
exhaust, never alienate, never be tortured by, never fear or distrust, and
never dream of regretting."

- spoken by Merlyn the Magician in T. H. White's, *The Once and Future
King*