There is a lot of talk lately about polarization and tribalism. The danger of fracture and schism feels immediate and frightening. Yeats’ oft-cited lines ricochet in my head almost daily. “Things fall apart; the centre cannot hold.” But it turns out that Yeats’ poem, published in 1920, was voicing a timeless sentiment. Another of my favorite poems, John Donne’s Anatomy of the World voiced a similar lament in 1619: And new philosophy calls all in doubt,The element of fire is quite put out,The sun is lost, and th’earth, and no man’s witCan well direct him where to look for it.And freely men confess that this world’s spent,When in the planets…