Erasmus Darwin Together Quotations

Hence when a person is in great pain, the cause of which he cannot remove, he sets his teeth firmly together, or bites some substance between them with great vehemence, as another mode of violent exertion to produce a temporary relief. Thus we have the proverb where no help can be has in pain, 'to grin and abide;' and the tortures of hell are said to be attended with 'gnashing of teeth.'Describing a suggestion of the origin of the grin in the present form of a proverb, 'to grin and bear it.'