Hanns Eisler is not only one of the most productive and versatile musicians of the 20th century, but his name also stands for the idea of "political composing" under the unique, often contradictory conditions of his time and ours. The ideological debates surrounding the person and work of the composer, which have taken place in the past under varying circumstances, have often obscured the intelligence and beauty of his music. This biography, published in honor of his 100th birthday, addresses the renewed interest in his oeuvre by providing readers with comprehensive material about Eisler's life for the first time. The author has spent 30 years studying Hanns Eisler and was able to draw on a wealth of previously unpublished documents and images from both public and private collections for his book.