In Slawomir Mrozek's "The Emigrants," truth comes from simple things. The title characters in this bitterly ironic play are two impoverished exiles from an unnamed European country. The simple-minded laborer is obsessed with the dream of returning to his native country a rich man, while his roommate, the coolly intellectual political refugee, keeps dashing such illusions. This dark comedy reminds us of what makes home a home, whether or not we are there.