I remember reading many years ago a statement from Dogen Zenji (and I've racked my brains trying to remember exactly where) that five minutes of concentrated zazen would diminish many years of accumulated bad/negative karma. What is the consensus on this matter? Does zazen have a positive karmic effect, or effects, on the practitioner? I do realise that all actions, speech, and thought have karmic effects: However, I am specifically making the positive karmic effect/s of zazen the subject of these questions, so I am not ignoring the obvious.