In Andean Perú, spirits are said to inhabit rocks, rivers, and mountain peaks with the intent of keeping a watchful eye on travelers passing through highland roads. The apu is one of the more well-known spirits that is sometimes portrayed as a minor deity with a mischievous side who is rarely seen. Simple folk song and a solemn prayer often successfully placate the apu to ensure safe passage through the mountains.  

Apu: Tone Poem for Orchestra begins with a short folkloric song inspired by the agile “pinkillo” flute, a small slender instrument that packs well into the small bags of travelers who must travel light. It is followed by the extended “haillí” of the second movement, a prayer to the apu, which flows attacca to the third movement in which the apu makes its brief but brilliant and dazzling appearance before disappearing once again into the mountain peaks. —Gabriela Lena Frank