Gregory the Great, on Isa 56:10

“His watchmen are all blind, they are all ignorant: dumb dogs not able to bark, seeing vain things, sleeping and loving dreams.”

“Sometimes in sacred speech preachers are understood by dogs. For the tongue of a dog, when it licks a wound, heals it, because holy teachers too, when they instruct us in the confession of our sin, touch as it were the wound of the mind through their tongue; and because by speaking they rescue us from sins, by touching wounds as it were they restore us to health. For that by the name of dogs the tongue of preachers is signified, the Lord says through the Psalmist: "The tongue of your dogs from enemies, from him." For from the unbelieving Jews the holy preachers were chosen, who, coming against thieves and robbers in defense of the truth, gave great barkings, so to speak, for the Lord. Against this it is said of certain reprobates: "Dumb dogs, not able to bark." Because therefore holy preachers condemn sins, but approve the confession of sins, saying: "Confess your sins to one another, and pray for one another, that you may be saved," dogs lick the sores of Lazarus.”

Imported from an open dataset — not yet checked against the printed edition.