When the blessed Eulogius saw an angel distributing gifts to the monks who toiled at all-night vigils, to one he gave a gold piece with the image of Our Lord Jesus Christ, to another a silver piece with a cross, to another a copper piece, to another a bronze piece, and to another nothing. The others who had remained in the church, left the church empty-handed. It was revealed to him that the ones who had obtained the gifts are those who toil at vigils and are diligent in prayers, supplications, psalms, chants, and readings. Those who received nothing or who left the church empty-handed are those who are heedless of their salvation, are enslaved to vainglory and the clamors of life, and stand feebly and lazily at vigils and whisper and jest.
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.
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.
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.