Why do the priest and deacon kiss the altar at the beginning and end of the Mass?
The kiss is intended as a sign of reverence for the altar as the place of sacrifice and as a symbol of Christ Himself. During the Middle Ages, it was also directed to the relics of confessors and martyrs that were enclosed in the altar.
Why is incense used at various times during the Mass?
The use of incense in worship started more than 2,000 years before Christianity even began. Incense is noted in the Talmud and is mentioned 170 times in the Bible. (e.g., Exodus 30: 1) It was a definite influence in the Church’s use of it in the liturgy. The burning of incense is an image of the prayers of the faithful rising to heaven. Incense is a sacramental, used to sanctify, bless, and venerate. The smoke from the incense as it rises upward is symbolic of the mystery of God Himself. The smell conveys the sweetness of Our Lord’s presence and the imagery reinforces how the Mass is linked to Heaven and Earth, ending in the very presence of God. At Mass incense may be used:
During the entrance procession
At the beginning of Mass to incense the altar and the cross
Before the Gospel reading
To incense the offerings of bread and wine, the cross, the altar, the priest, and finally the people.