Many years ago it was assumed that cultured people would share a body of core knowledge. That's why, for example, the "classics" were studied at all liberal arts colleges. That's no longer true in today's world, but perhaps the idea of Core Knowledge is still relevant in trying to defuse the polarization and tribalism that has become so dominant in the United States. That hypothesis is the basis for the booklists you'll see organized here.  Suggestions welcome!