I believe that planting these oaks is necessary not only in biospheric terms, that is to say, in the context of matter and ecology, but in that it will raise ecological consciousness-raise it increasingly, in the course of the years to come, because we shall never stop planting.

Joseph Beuys (1982), cited in: Jeffrey Kastner, Brian Wallis (1998), Land and environmental art. p. 164 : about his 7,000 Oaks [see there the image].