The German Romantic poet Friedrich Hölderlin spent most of his life in isolation in a tower on the banks of the Neckar river, following a mental illness. His poems have long fascinated composers. 2020 marks the 250th anniversary of his birth. The Nicaraguan-British composer Geoffrey Álvarez’s monumental song cycle, “Hölderlinfenster” imagines the poet through a “frame” of Schubert’s “Schwanengesang”. Poet and composer never met in real life but perhaps here their spirits do. Álvarez writes music of great intensity and intimate drama on a sometimes epic scale. His highly personal tonal language defies easy categorization but conveys a “Hölderlin river journey” with admirable expressiveness.