Paul prays for the Ephesians (14-21). It is worth noting what he prays for. He prays that they may be strengthened in the inner being. The early church was under constant threat of persecution. The church in and around Ephesus was challenged one very side by the government, by the prevailing religions of the region, by various philosophies, by economic pressure, etc. In order to be all that the church needs to be we have to be strengthened on the inside -- our hearts, our wills, our inner beings. He prays that Christ may dwell in us and that we would be "rooted and grounded in love (17)." What does it mean to be "rooted and grounded in love?" I think he means that love becomes the prevailing philosophy of all that we do. We teach and preach because of love, we help and encourage because of love, we challenge and confront because of love, and we do all that we do because of love.
He prays for comprehension. In Gnostic Ephesus the prevailing religion and philosophy taught that everyone needed to have a "special knowledge" in order to attain salvation. Paul is saying that we can know the breadth, length, height and depth . . . so that we may be filled with the fullness of God. At Christ followers we don't stop with any special "head knowledge" of God. It is not knowing about God, it is knowing in a personal and intimate way the creator of the universe through his son Jesus Christ. Notice in verse 19 that Paul says this "surpasses knowledge" -- in Greek it surpasses gnosis. In this we are filled with the fullness of God.