Compos mentis

‘[…] you have my hearty consent, sir, to marry the girl whensumdever it’s convenient.’ Dame Mayrose finished her speech with a low courtesy, and Tom Sponge sat like a petrified image. ‘For God’s sake, Mrs. Mayrose, are you compos mentis?’ said he. ‘Please your honour, I don’t understand no foreign languages,’ said the good woman, ‘but my darter tells me you want to make proposhalls.’