Trance/hypnosis is OK, in terms of it being without conflict. "Concentration" is "NOT OK" because concentration is a FALSE concept, it does not really exist because there is effort in it, so the horizontal conflict (the concentrator trying to be concentrated). What goes by the name of "concentration" is a struggle, although the struggle of "concentration" can maybe change into hypnosis (but those two cannot exist at the same time).

So it can be said that UP/Yoga/Dhjana/Zen is the whole unobstructed movement in and out of hypnosis/trance and what is NOT It is the struggle to get "there" or "somewhere" called concentration, effort, horizontal conflict, goal, purpose, end in view, the idol, desire, fear, etc.