Here's what I think it a good answer to this question by Bernie Glassman who was the Senior Monk at ZCLA when I was attending there and later became a full-fledged Zen Master. He's since renounced his Zen Master title and goes about his zen practice in a much more low-key and casual manner. It's refreshingly simple and to-the-point without any Buddhist or Sanskrit mumbo-jumbo: What is Enlightenment? <http://zenpeacemakers.org/2013/03/what-is-enlightenment/>
Bernie Glassman ...Bill!
