The candles lit before the icons of the Theotokos are a symbol of the fact that She is the Mother of the Unapproachable Light, and also of Her most pure and burning love for God and Her love for mankind.
One of the fathers used to say that some old men were sitting one day and talking of what was useful to the soul. One of them had the gift of vision, and he saw angels who were waving branches in honor of the old men, but when one of them began to speak of irrelevant things the angels withdrew, and some pigs walked amongst the old men bringing a bad smell and messing up everything. As soon as they began once again to speak of what was useful to the soul, the angels returned to do them honor.
There are three things that impel us towards what is holy: natural instincts, angelic powers and probity of intention. Natural instincts impel us when, for example, we do to others what we would wish them to do to us (cf. Luke 6:31), or when we see someone suffering deprivation or in need and naturally feel compassion. Angelic powers impel us when, being ourselves impelled to something worthwhile, we find we are providentially helped and guided. We are impelled by probity of intention when, discriminating between good and evil, we choose the good.
Even if we have thousands of acts of great virtue to our credit, our confidence in being heard must be based on God's mercy and His love for men. Even if we stand at the very summit of virtue, it is by mercy that we shall be saved.
The Law (as it is written in the Scriptures) was given to us by Angels and, both before and after the days of the Law, Angels guided our illustrious forefathers to God, either by declaring to them what they should do and leading them from error and an evil life to the straight path of truth, or by making known to them the Divine Law, or in the manner of interpreters, by showing to them holy Hierarchies, or secret visions of super-mundane Mysteries, or certain divine prophecies. Now if anyone should say that God has shown Himself without intermediary to certain holy men, let him know beyond doubt, from the most Holy Scriptures, that no man has ever seen, nor shall see, the hidden Being of God; but God has shown himself, according to revelations which are fitting to God, to His faithful servants in holy visions adapted to the nature of the seer.
You see how bright the sun and the stars are. 'Then shall the righteous shine forth as the sun' from the inner immaterial light of God. Whenever the angels appear upon earth, they are almost always surrounded by light. Aspire to that enlightenment. Throw aside the works of darkness. We can raise our nature to communion with the Divine Nature; and God is the Light uncreated, surpassing every light that has been created.
When the holy Abba Anthony lived in the desert he was beset by boredom, and attacked by many sinful thoughts. He said to God, 'Lord, I want to be saved but these thoughts do not leave me alone; what shall I do in my affliction? How can I be saved?' A short while afterwards, when he got up to go out, Anthony saw a man like himself sitting at his work, getting up from his work to pray, then sitting down and plaiting a rope, then getting up again to pray. It was an angel of the Lord sent to correct and reassure him: 'Do this and you will be saved.' At these words, Anthony was filled with joy and courage. He did this, and he was saved.
The candles burning on the altar represent the non-created Light of the Trinity, for the Lord dwells in an unapproachable light. They also represent the fire of Divinity which destroys our ungodliness and sins. The candles lit before the icons of the Savior signify that He is the True Light which lighteth every man that cometh into the world (John 1:9); at the same time, He is a Fire which engulfs and revives our souls and bodies.
Whenever we enter the church and draw near to the heavenly mysteries, we ought to approach with all humility and fear, both because of the presence of the angelic powers and out of the reverence due to the sacred oblation; for as the Angels are said to have stood by the Lord's body when it lay in the tomb, so we must believe that they are present in the celebration of the Mysteries of His most sacred Body at the time of consecration.
He stands, then - but not alone, for before Him go angels, saying: 'Lift up the gates, O ye the princes.' What gates? Even those of which the Psalmist sings in another place also: 'Open to me the gates of righteousness.' Open, then, thy gates to Christ, that He may come into thee - open the gates of righteousness, the gates of chastity, the gates of courage and wisdom. Believe the message of the angels: 'Be ye lifted up, ye everlasting doors, and the King of Glory shall come in, the Lord of Sabaoth.'
Since the angels and souls are incorporeal beings, they are not in a particular place, yet neither are they everywhere. They do not sustain all things, but themselves depend on Him Who sustains them. Hence they, too, are in Him Who sustains and embraces all things, and they are appropriately delimited by Him. The soul, since it sustains the body with which it is created, is everywhere in the body, although not in the sense of being located in a place or encompassed; but it itself sustains, encompasses and quickens the body, by virtue of the fact that it is in God's image.
Also in another place it shows that the angels are the ministers of the saints. For when Elijah was on the mountain and foreigners were rising up against him, his servant said, 'Many are coming against us and we are all alone.' Then Elijah answered, 'Do you not see the armies and multitudes of angels with us surrounding us to aid us?' (2 Kg. 6:15). You see how the Master and the multitude of angels are standing by the side of their servants.
Have confidence in the compassion of our Creator. Reflect well on what you are now doing, and keep before you the things you have done. Lift up your eyes to the overflowing compassion of heaven, and while He waits for you, draw near in tears to our merciful Judge. Having before your mind that He is a Just Judge, do not take your sins lightly; and having also in mind that He is compassionate, do not despair. The God-Man gives man confidence before God.
When the intellect is pure, sometimes God Himself approaches and teaches it; and sometimes the angelic powers, or the nature of the created things that it contemplates, suggests holy things to it.
The candles lit before icons of saints reflect their ardent love for God for Whose sake they gave up everything that man prizes in life, including their very lives, as did the holy apostles, martyrs and others. These candles also mean that these saints are lamps burning for us and providing light for us by their own saintly living, their virtues and their ardent intercession for us before God through their constant prayers by day and night. The burning candles also stand for our ardent zeal and the sincere sacrifice we make out of reverence and gratitude to them for their solicitude on our behalf before God.