"Our minds must have relaxation: rested, they will rise up better and keener. Just as we must not force fertile fields (for uninterrupted production will quickly exhaust them), so continual labor will break the power of our minds. They will recover their strength, however, after they have had a little freedom and relaxation."
Lucius Annaeus Seneca
(4 B.C.-A.D. 65) Roman Stoic philosopher, statesman, dramatist, "Seneca the Younger"
On Tranquility of the Mind, A letter to Serenus as translated in Tranquillity of Mind and Providence (1900) by William Bell Langsdorf.