Doing some character analysis according to what or who a character swears by would be a completely fascinating study. It seems that mostly comic figures swear by the mass. Rosalind in As You Like It swears by Jupiter. She’s the only one in the play who does, though not the only one in the canon.
I don’t know. I haven’t done the study yet – but I’d like to see a list of all of Shakespeare’s characters and who/what they swear by. The mass is a curious one. Is he swearing by a Catholic mass? A church service of some other kind? Or is he swearing by the physical substance of something? The mass of forgetting? Or the mass of remembering?