Sri Krishna describes three kinds of joy. One is Bishayananda, the joy of Bishaya, object in the world. The other two are Bhajananda and Brahmanaanda which culminate in visions or extraordinary joys. And the final kind is the Akman itself, which is joy itself. It's fulfillment because it is infinity. You are without limit. There is no second reality apart from you. This knowledge when it dawns, it is the highest fulfillment.