A prolific poet and essayist, Denise Levertov was the author of more than twenty books, the last of which were A Door in the Hive (1989), Evening Train (1992), The Sands of the Well (1996), The Life Around Us: Selected Poems on Nature (1997), and The Stream & the Sapphire: Selected Poems on Religious Themes (1997).  She taught for many years at Stanford University and died in 1997 at the age of 74.