Divine Grace dwells in the holy icon, just as it dwells in the body and blood of Christ, or in the Holy Cross and the relics of the saints. This is why so many miracles have occured down through the ages through icons and relics: it is the indwelling grace of God.
Historical records reveal that from the very beginning of the Church, holy icons have been and inseparable part of the worship of the people of God. From East to West, there are preserved early iconography on the walls of caves of Cappadocia to the catacombs of Rome where Christians met to worship.
St. John of Damascus called icons the “open books of the illiterate.” St. Basil the great compared the icon to a sermon. He explained that it is not only the illiterate who learn from the icon, but all the faithful as we are all edified by a well written, well-prepared sermon.
Today, most all of us are not illiterate. If you read your Bible every day, that is a blessing upon you. However, if you do not read your Bible every day, then you might take a moment each day to look into an icon and learn of the sacred truths God has revealed to us. That too is a blessing upon you.
Icons are also windows to heaven, where the saints look down upon us and where the faithful also look up to God. When our Church is filled with many beautiful icons depicting the life of Christ and His saints, we can transcend our material and secular world and ascend to the spiritual realm.
This is the Orthodox Tradition from the time of the Early Christian Church to the present. The Grace of God does not change, as it says in the Epistle to the Hebrews (13:8): Jesus Christ is the same yesterday and today and for ever.