Here are some examples of how Cage refers to Thoreau and his writings in his own compositions. The examples are taken from all three art forms Cage engaged in: poetry, music and the visual arts.
Thoreau in Cage
Excerpt from Mureau (1970)
From Empty Words - Part I (1974)
From Empty Words - Part  IV (1975)
First page of Renga (1975-76)
From 17 Drawings by Thoreau (1978)