The Gospel for Sunday is the parable of "The Pharisee and the Publican." In his Commentary on the Gospel of Luke (Liturgical Press: Sacra Pagina Series), Luke Johnson writes:
The parable itself is one that invites internalization by every reader because it speaks to something deep within the heart of every human being. The love of God can so easily turn into an idolatrous self-love; the gift can so quickly be seized as a possession; what comes from another can so blithely be turned into self-accomplishment. Prayer can be transformed into boasting. Piety is not an unambiguous posture.
The literary skill revealed by the story matches its spiritual insight. The pious one is all convoluted comparison and contrast; he can receive no gift because he cannot stop counting his possessions. His prayer is one of peripheral vision.
Of course, "praying" with peripheral vision is not praying at all.