Virgil, Aeneid VI.126-129
Melphi speaks
facilis descensus Averno;
noctes atque dies patet atri ianua Ditis;
sed revocare gradum superasque evadere ad auras,
hoc opus, hic labor est.
The priest translates
«The descent to Avernus is easy: night and day the door of dark Dis stands open; but to call back your step and escape to the air above, that is the task, that is the labor.»
And interprets
This line speaks to you of going down and climbing back. Falling into a habit that hurts you, into debt, into a relationship that dims you, into a season of distrust, is easy: the door is always open, night and day. The real work begins when you decide to come back up. If you are in such a moment, do not be ashamed of having gone down: it happens to everyone. But recognize that the climb asks more strength than the fall, and prepare accordingly. If instead you are about to go down, stop for a moment before the threshold. This is not a sentence but a warning: getting in costs little, getting out costs a lot. Decide knowing it.
The historical translations
Lo scender ne l’Averno è cosa agevole,
Chè notte e dì ne sta l’entrata aperta;
Ma tornar poscia e riveder le stelle,
Qui la fatica e qui l’opra consiste.
Anchises' son, the downward path to death
Is easy; all the livelong night and day
Dark Pluto's door stands open for a guest.
But O! remounting to the world of light,
This is a task indeed, a strife supreme.