I think I know what Shakespeare meant for Portia to be saying when he wrote this dialog between Shylock and Portia, and I found a decent discussion on the web here.
What I want to know is, what do people mean, when they quote this figure-of-speech by itself. It seems to have acquired a meaning of its own, a proverb that in the end, embodies some meaning which maybe is supposed to be clear to everybody, but which is not clear to me.
Is it used by those who quote it, for example, meant as a rejoinder or insult against someone who seems stubborn, recalcitrant, and uninterested in the mores of the larger society? Has anyone seen a cataloging of other places in literature where this quote is used, or is the quote largely used in conversation only?