This work explores the troubled relationship and unfinished intellectual dialogue between Paul Celan, regarded by many as the most important European poet after 1945, and Martin Heidegger, perhaps the most influential figure in twentieth-century philosophy. It centers on the persistent ambivalence Celan, a Holocaust survivor, felt toward a thinker who respected him and at times promoted his poetry. Celan, although strongly affected by Heidegger's writings, struggled to reconcile his admiration of Heidegger's ideas on literature with his revulsion at the thinker's Nazi past. That Celan and Heidegger communicated with each other over a number of years, and in a controversial encounter, met in 1967, is well known. The full duration, extent, and nature of their exchanges and their impact on Celan's poetics has been less understood, however. In the first systematic analysis of their relationship between 1951 and 1970, James K. Lyon describes how the poet and the philosopher read and responded to each other's work throughout the period. He offers new information about their interactions before, during, and after their famous 1967 meeting at Todtnauberg. He suggests that Celan, who changed his account of that meeting, may have contributed to misreadings of his poem "Todtnauberg." Finally, Lyon discusses their two last meetings after 1967 before the poet's death three years later. Drawing heavily on documentary material--including Celan's reading notes on more than two dozen works by Heidegger, the philosopher's written response to the poet's "Meridian" speech, and references to Heidegger in Celan's letters--Lyon presents a focused perspective on this critical aspect of the poet's intellectual development and provides important insights into his relationship with Heidegger, transforming previous conceptions of it.