In 1988 the Polish playwright Slawomir Mrozek was invited by the Nobel Foundation and the Royal Theatre in Stockholm to deliver a speech for the ‘Strindberg-O'Neill’ symposium on the issues suggested by this title. In defining his terms and their relationship, he combined Aristotelian precision and existential candour with a gentle irony entirely his own. The speech was first printed in the Polish theatre journal Dialog, to whose editors we are grateful for permission to print this translated version.