With the material picture before our eyes we see the invisible God through the visible representation, and glorify Him as if present, not as a God without reality, but as God who is the essence of being. Nor are the saints whom we glorify fictitious. They are in being, and are living with God; and their spirits being holy, they help, by the power of God, those who deserve and need their assistance.
St. John Damascene
Apology Against Those Who Decry Holy Images
Part III, Quote from Simeon of Mount Thaumastus