The theme of jealousy is well known to readers of Marcel Proust's In Search of Lost Time, and its epistemological function has been dissected by critics such as Girard, J. Hillis Miller, and Bowie. This article builds on the insights of these theorists but from the altered perspective of Heideggerian philosophy. Heidegger provocatively argues that Western philosophy has concerned itself with epistemology at the expense of ontology; the function of jealousy will be considered in these terms. That is to say, rather than operating as an epistemological tool, Proustian jealousy is a "mood" that discloses being.