"Window" is a symbol of the Source of the Divine spiritual Light of Truth - His Will, expressed in His Commandments, in the Teachings of Christ, the Prophets, the Apostles, through whose preaching it is possible to see, evaluate, perceive oneself, one's actions and all the events of the world around.
"Window" is also the image of all the Righteous, who through the purity of their pious life and the preaching of the Will of God open to the peoples a spiritual "Window" - the "Light" of the true knowledge of God's Commandments.