E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Slough of Despond.
A deep bog which Christian has to cross in order to get to the Wicket Gate. Help comes to his aid. Neighbour Pliable went with Christian as far as the Slough, and then turned back again. (Bunyan: Pilgrims Progress, part i.).