E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Momus.
One who carps at everything. Momus, the sleepy god, was always railing and carping.
1
Momus, being asked to pass judgment on the relative merits of Neptune, Vulcan, and Minerva, railed at them all. He said the horns of a bull ought to have been placed in the shoulders, where they would have been of much greater force; as for man, he said Jupiter ought to have made him with a window in his breast, whereby his real thoughts might be revealed. Hence Dr. Gray says that every unreasonable carper is called a Momus.