Seneca, On the Shortness of Life.
"Some take a break in the middle of the day and keep any less demanding task for the afternoon hours. Our ancestors also forbad any new motion to be introduced in the senate after the tenth hour. The army divides the watches, and those who are returning from an expedition are exempted from night duty. We must indulge the mind and from time to time allow it the leisure which is its food and strength. We must go for walks out of doors, so that the mind can be strengthened and invigorated by a clear sky and plenty of fresh air. At times it will acquire fresh energy from a journey by carriage and a change of scene, or from socializing and drinking freely.
"Occasionally, we should even come to the point of intoxication, sinking into drink but not being totally flooded by it; for it does wash away cares, and stirs the mind to its depths, and heals sorrow just as it heals certain diseases. Liber was not named because he loosens the tongue, but because he liberates the mind from its slavery to cares, emancipates it, invigorates it and emboldens it for all its undertakings. But there is a healthy moderation in wine, as in liberty. Solon and Arcesilas are thought to have liked their wine, and Cato has been accused of drunkenness; whoever accused him will more easily make the charge honorable than Cato disgraceful. But we must not do this often, in case the mind acquires a bad habit; yet at times it must be stimulated to rejoice without restraint and austere soberness must be banished for a while.
"For whether we agree with the Greek poet that 'Sometimes it is sweet to be mad,' or with Plato that ' A man sound in mind knocks in vain at the doors of poetry,' or with Aristotle that 'No great intellect has been without a touch of madness,' only a mind that is deeply stirred can utter something noble and beyond the power of others.
"When it has scorned everyday and commonplace thoughts and risen aloft on the wings of divine inspiration, only then does it sound a note nobler than mortal voice could utter. As long as it remains in its senses it cannot reach any lofty and difficult height: it must desert the usual track and race away, champing the bit and hurrying its driver in its course to a height it would have feared to scale by itself.
"So here you have, my dear Serenus, the means of preserving your tranquility, the means of restoring it, and the means of resisting the faults that creep up on you unawares. But be sure of this, that none of them is strong enough for those who want to preserve a fragile thing, unless the wavering mind is surrounded by attentive and unceasing care."