Holy icons serve a number of purposes:
- They enhance the beauty of a church.
- They instruct us in matters pertaining to the Christian faith.
- They remind us of this faith.
- They lift us up to the prototypes which they symbolize, to a higher level of thought and feeling.
- They arouse us to imitate the virtues of the holy personages depicted on them.
- They help to transform us, to sanctify us.
- They serve as a means of worship and veneration.
The most obvious function of icons is that they enhance the beauty of a church. Attention to this fact is called by the following hymn from the Triodion that is chanted on the eve of the Sunday of Orthodoxy, when the victory over Iconoclasm is commemorated: The Church of Christ is now embellished like a bride, having been adorned with icons of holy form; and it calls all together spiritually; let us come and celebrate together joyfully with concord and faith, magnifying the Lord.
The idea that icons are a means of enhancing the beauty of churches appears in many writings of the Fathers. To give one example, Niketas Stethatos, the most famous disciple of St. Symeon the New Theologian (949-1022), says that upon becoming abbot of the Monastery of St. Mamas, Symeon “adorned its church with beautiful marbles on the pavement, with holy icons, and other wonderful offerings.” It may be added, that the very fact that the Orthodox in general speak of the ‘decoration’ (diakosmesis) of churches with icons shows plainly that they recognize this function.
As a ‘house of God’ and a ‘house of prayer,’ the church should be rendered as beautiful as possible, especially in the interior, where the faithful gather for worship. But the beauty of the church must bear the impress of holiness; and the pleasure evoked by it must transcend that of mere aesthetic experience: it must be spiritual.
That icons serve to instruct the faithful is a point which is duly emphasized by the Greek Church Fathers. Thus, St. John Damascene remarks that since not every one is literate, nor has leisure for reading, the Fathers agreed that such things as the Incarnation of our Lord, His association with men, His miracles, His Crucifixion, His Resurrection, and so on, should be represented on icons.  And St. Photios, Patriarch of Constantinople, says: “Just as speech is transmitted by hearing, so a form through sight is imprinted upon the tablets of the soul, giving to those whose apprehension is not soiled by wicked doctrines a representation of knowledge consonant with piety.” 
Photios adds that icons not only teach, as do written accounts, but in some instances they are more vivid than written accounts, and hence superior to the latter as a means of instruction. He cites as an example the representation of the deeds of holy martyrs.
We can also appreciate the effectiveness of icons as a means of instructing if we note that in a composition, such as the Nativity, the Raising of Lazarus, or the Crucifixion, the icon presents simultaneously and concisely many things—a place, persons and objects—that would take an appreciable period of time to describe in words.
We have a tendency to forget, to forget even things that are of vital importance to us, to fall asleep spiritually. So even though we may know many things about the Christian faith, such as the commandment of love, the teaching about the spiritual realm, the exemplary character and noble deeds of many holy personages, we tend to forget them, as we become preoccupied with everyday worldly matters and pursuits. Icons serve to remind us of these things, to awaken us with respect to them. The vivacity of icons, which St. Photios points out, renders icons very effective in this regard. John Damascene sums up this function when he calls them concise memorials (hypomneseis), that is, concise means of remembering. He gives the following example: “Many times, doubtless, when we do not have in mind the Passion of our Lord, upon seeing the icon of Christ’s Crucifixion, we recall His saving suffering.” 
Icons also serve to lift us to the prototypes, to a higher level of consciousness, of thought and feeling. This is their anagogic function. The prototypes of the icons, i.e. Christ, the Theotokos, the Prophets, Apostles, Martyrs, Saints in general, enjoy a higher level of being than we do in our ordinary, distracted everyday life. When we see their icons, we recall their superior character and deeds; and as we recall them, we think pure, sublime thoughts, and experience higher feelings. Thus, for a while we live on a higher plane of being. As St. John Damascene remarks, “we are led by perceptible icons to the contemplation of the divine and spiritual.”  In this function of the icon, its essentially symbolic nature is manifest. An icon is not an end in itself; it is not merely an aesthetic object to be enjoyed for whatever artistic merits it possesses, but is essentially a symbol, carrying us beyond itself. It is designed to lead us from the physical and psychophysical to the spiritual realm. And hence it is, as St. John Damascene says, a pattern (typos) of something heavenly.
By instructing us in the Christian religion, reminding us of its truths, aims and values, and lifting us up to the prototypes, to holy personages, icons serve another important purpose: they stir us up to imitate the virtues of such personages. Thus, one of decrees of the Seventh Ecumenical Synod—the Synod that was convoked specially to settle the dispute between the iconoclasts and those who defended the veneration of holy icons—says: “The more continually holy personages are seen in icons, the more are the beholders lifted up to the memory of the prototypes and to an aspiration after them.” 
An additional function served by holy icons is to help transform our character, our whole being, to help sanctify us. They effect this by instructing us, reminding us, uplifting us, and stirring us up morally and spiritually. The function of the icon in this regard is based on the principle that we become like that which we habitually contemplate. True icons focus the distracted, dispersed soul of man on spiritual perfection, on the divine. By dwelling steadily and lovingly on such perfection, we come to partake of it more and more.
Finally, the icon has a liturgical function, it is a means of worship and veneration. This is one of its primary functions, more important than the first. Like sacred hymns and music, the icon is used as a means of worshipping God and venerating His saints. As such, it is essentially symbolic, leading the soul from the visible to the invisible, from the material to the spiritual, from the symbol to the prototype or original which it represents. As every Orthodox Christian knows, the first act of the faithful upon entering a church is to take a candle, light it and put it on a candlestand that is placed next to the proskynetarion or icon-stand on which is set the icon representing the sacred person, persons or event specially celebrated by the particular church and after whom or which it is named. Then he bows before the icon, making the sign of the cross, and kisses the icon, saying a brief prayer. This series of acts is called veneration or ‘honorable reverence’ of the icon. It is not an act of worshipping the icon. The Greek Church Fathers distinguish very sharply between ‘honorable reverence’ (timetike proskynesis), which is accorded to icons, and ‘worship’ (latreia). Worship is accorded only to God. Further, they emphasize that the veneration which we give to a holy icon goes to the prototype which it represents, for example, to Christ, to the Theotokos, to some martyr or other saint. In the words of Basil the Great, which have been repeated by John Damascene and other defenders of the icons, “the honor which is given to the icon passes over to the prototype” (he time tes eikonos eis to prototypon diabainei). The prototype honored is in the last analysis God, as God created man in His own image. 
Neither God nor the saints, of course, need the honor which we offer them, be it by means of icons, or by means of hymns and music. But it is only proper for us to do so, as the adoration of God and the admiration of saints are expressions of a soul that sees and loves the beauty of holiness, of spiritual perfection, and feels grateful to the Deity and to holy men for their many benefactions to mankind. Such a response is not merely something proper for us, but is also conductive to our salvation. The following remark of John Damascene calls attention to this point, and at the same time has a bearing on several of the functions served by icons: “I enter the common place-of-therapy of souls, the church, choked as it were by the thorns of worldly thoughts. The bloom of painting attracts me, it delights my sight like a meadow, and secretly evokes in my soul the desire to glorify God. I behold the fortitude of the martyr, the crowns awarded, and my zeal is aroused like fire; I fall down and worship God through the martyr, and receive salvation.” 
When the various important functions of icons are ignored and the crucial distinction between honorable reverence and worship is lost sight of, iconoclasm, the condemnation of icons, is a result. This is what happened in 726, when the Byzantine Emperor Leo the Isaurian issued an edict which condemned the making and veneration of icons as idolatry, and contrary to the second commandment. But the icon, as we have seen, is an image or symbol, and is designed to lead us to that of which it is an image or symbol, whereas an idol lacks this power of the authentic symbol; and the veneration of an icon is not an act of ‘worshipping’ it. Hence the charge of idolatry shows gross ignorance with regard to the nature and functions of icons.
In connection with the practice of according the reverence of honor to holy icons, it should be remarked that this is deeply rooted in the sacred tradition of Christianity. St. John Damascene would trace the tradition of honorable reverence of sacred objects back to the Mosaic people, who “venerated on all hands the tabernacle which was an image and type of heavenly things, or rather of the whole creation.” The cross has always been venerated by Christians. The painting of the cross in the dome or apse of the Church was not forbidden in Byzantium even by the fanatical enemies of the icons, the Iconoclasts. Now the crucifix is itself an icon, an image of Christ’s crucifixion, a symbol of Christ Himself, Who is usually depicted upon it in the Eastern Orthodox Church.
- Triodion, Venice, 1876, p. 123.
- The Extant Works of Saint Symeon the New Theologian, trans. by Dionysios Zagoraios, Syros, 1886, p. 6.
- See the excerpt from St. John Damascene in Appendix A below.
- Cyril Mango, The Homilies of Photius, p. 294. Cf. St. Basil: “What the spoken account presents through the sense of hearing, the painting silently shows by representations” (P.G., Vol. 94, col. 1401a).
- P.G., Vol. 94, col. 1261a.
- St. Basil, Concerning the Holy Spirit, Ch. 18.
- P.G., Vol. 94, col. 1268 a-b.
This is Chapter III from Orthodox Iconography (Belmont, MA: Institute for Modern Greek and Byzantine Studies, 1992 ), pp. 30-35. Reprinted with the kind permission of Dr. Cavarnos. His many excellent works can be found in any good Orthodox bookstore. A catalogue can be obtained by contacting the Institute for Byzantine and Modern Greek Studies, 115 Gilbert Road, Belmont, MA, 02178.