theraccolta:

A beautiful tradition that is used by the Church in the Sacraments and other devotions. God made use of fire and flames many times in the Old and New Testaments. He appeared to Moses in the form of a fiery bush; the Holy Spirit descended on the Apostles in the form of fiery tongues; and Christ is often referred to as the “light of the world to enlighten them that sit in the darkness and the shadow of death.” The lighted candles remind us of all this. They have the effect of expelling devils and bringing blessings to the places were they are lighted. 

The prayer that the priest says for the blessing of the candles is beautiful:

“O Lord Jesus Christ, Son of the Living God, we implore Thee to bless these candles and through the power of the holy Cross, to bestow upon them Thy heavenly benediction, who has given them to mankind to dispel darkness. 

“May they, through the sign of the Holy Cross, obtain such blessing that wherever they may be lighted or wherever they be placed the powers of darkness may vanish, trembling and affrighted, with all their aids and accomplices and be driven from these dwellings, and never again dare disquiet or molest them that serve Thee, Almighty God.”

Blessed candles are made with pure beeswax to symbolize the pure flesh of Christ received from His Virgin Mother; the wick symbolizes the soul of Christ, and the flame that emits light and heat, His Divinity. During exposition of the Blessed Sacrament, the Host is surrounded by candles. A sanctuary lamp burns continuously before all tabernacles to honor His Divine Presence. 

Many pious Catholics light votive candles as a symbol of their prayers rising constantly before the throne of God, Our Lady, or the specific Saint to which he is praying. Candles add beauty, symbolism and solemnity to all the liturgical functions.