Written in 1975 as a birthday greeting to the theologian Hans Urs von Balthasar, Klaus Hemmerle's Theses Towards A Trinitarian Ontology is of the highest theological moment as a key source text for the recent widespread interest in the idea of a "Trinitarian ontology." Drawing on Hemmerle's deep familiarity with German Idealism, the Theses sketch an ontology beginning not from invariance, but from "self-giving," from kenosis, and articulate a distinctively Trinitarian response to the aporias of early twenty-first-century thought-a response for which only Love can credibly be understood as the meaning of Being.