Notice that both the Pharisee and the tax collector pray while they are standing. Jesus says the tax collector would not even look toward heaven, which implies that the Pharisee did. This is the normal posture of prayer among Jews and Eastern Orthodox Christians today. The western practice of kneeling or sitting for prayer while bowing one s head is reserved for penitential occasions. Orthodox Christians do not sit for prayer because there are no seats.
Pews are a late medieval innovation in the west.
By saying that the tax collector couldn t even look God in the eye, so to speak, Jesus is emphasizing how repentant he was. If you live a life apart from God, you will indeed be crippled by any negative assessment of yourself, even if it is accurate, because the only source of power in your life is your optimism and your confidence in your own abilities. Therefore worldly people must strive for a positive self-image, even at the expense of inaccuracy. However, for those who serve God, an accurate self-image is more important than either a positive or a negative one, because if we esteem ourselves wrongly, it clouds our relationship with God. If we think too highly of ourselves, we delude ourselves into thinking we do not need God or that we are responsible for the blessings in our lives.