Seneca,
Moral letters to Lucilius — Letter 78…
“ Do you think that you are doing nothing if you possess self-control in your illness? You will be showing that a disease can be overcome, or at any rate endured. 21. There is, I assure you, a place for virtue even upon a bed of sickness. It is not only the sword and the battle-line that prove the soul alert and unconquered by fear; a man can display bravery even when wrapped in his bed-clothes. You have something to do: wrestle bravely with disease. If it shall compel you to nothing, beguile you to nothing, it is a notable example that you display. ”
