Oneness has this imperfection in articulatior linguistic articulation, because then it implies there's a border. Oneness can only be defined through negation until you realize linguistics or language is failing me to try to define this. It can only be felt. So that's what non dual means. Id be happy to give a a breakdown of what vedanta is in like, three minutes, if you want. Are you crazy?
James Beshara (Time Magazine 30 Under 30! Below The Line podcast! Non-dualist! Start-up Investor!) makes it weird!