This article is a translation from French of selected letters of the poet and playwright Paul Claudel to the composer Darius Milhaud. These letters were published in Paris in 1962 for the 70th anniversary of Milhaud (1892–1974), a few years after Claudel’s death (1868–1955). Also, these letters are a unique document testifying to the long cooperation of two outstanding representatives of the art and culture of France in the first half of the 20th century. One can find out from their letters how the work on their first joint project—the ancient trilogy “L’Orestie”—progressed. “L’Orestie” would later be considered as one of the most significant works of Milhaud and Claudel. The impetus for the beginning of cooperation was the cycle of romances “Knowledge of the East”—one of the first published works of the composer, written on the poems of Claudel even before meeting him. The correspondence began in 1912 and lasted 44 years until the poet’s death. During this time, Milhaud composed about 30 works on Claudel’s texts. This communication enriched both: Claudel came to the conclusion that it was necessary for music to participate in his dramas, and Milhaud received at the disposal of artistically valuable texts by Claudel.