Well, you dropped Linton with it into a Slough of Despond. He was in earnest: in love, really. As true as I live, he’s dying for you; breaking his heart at your fickleness
Emily Brontë. Wuthering Heights (1847)
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"Now, I saw in my dream, that just as they had ended their talk, they drew nigh to a very miry slough, that was in the midst of the plain; and they, being heedless, did both fall suddenly into the bog. The name of the slough was Despond."—BUNYAN.
George Eliot. Middlemarch
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Wherefore Christian was left to tumble in the Slough of Despond alone: but still he endeavoured to struggle to that side of the Slough that was still further from his own house, and next to the Wicket-gate; the which he did, but could not get out, because of the Burden that was upon his back: