The Rebbe taught this discourse in the week of Sedra Devarim in 1965, at the conclusion of his saying Kaddish for his mother,  Rebbetzin Chana. He edited and published the discourse in 1988 for the "shloshim', meaning 30 days after the passing of his wife Chaya Mushka.  It explains the link between death and the sin of the Tree of Knowledge and how the ultimate goal is to remove both sin and death from the world.