The other week, Radha, who teaches the Dharma Facilitators Programme in Oz, and I were talking on the phone about non-duality. She has a great love of the exploration and teaching of the non-dual. It is something we both share. I know she has given many years to this inquiry.
The Buddha, himself, never usd the term non-duality (advaita) in 5000 Pali suttas of his teachings.