facilis descensus Averni

From Virgil, Aeneid, VI-126. "The descent of Avernus is easy"; in ref. to Avernus, a deep lake near Puteoli, a reputed entrance to the underworld. "It is easy to slip into moral ruin"

Poe at the end of "The Purloined Letter" : "... For eighteen months the Minister has had her in his power. She has now him in hers; since, being unaware that the letter is not in his possession, he will proceed with his exactions as if it was. Thus will he inevitably commit himself, at once, to his political destruction. His downfall, too, will not be more precipitate than awkward. It is all very well to talk about the facilis descensus Averni; but in all kinds of climbing, as Catalani said of singing, it is far more easy to get up than to come down. In the present instance I have no sympathy - at least no pity - for him who descends. He is that monstrum horrendum, an unprincipled man of genius. ..."