William Barclay says the verse "blessed are the poor in spirit" means, "Blessed is the man who has realized his own utter helplessness, and who has put his whole trust in God. If a man has realized his own utter helplessness, and has put his whole trust in God, there will enter into his life two things. He will become completely detached from things, for he will know that things have not got it in them to bring happiness or security; and he will become completely attached to God, for he will know that God alone can bring him help, and hope, and strength. The man who is poor in spirit is the man who has realized that things mean nothing, and that God means everything."
ChristianGlobe Networks, Inc., The Beatitudes Are Not Platitudes!, by Mickey Anders