In the fullness of the celebration of the Mass, after the Priest prays the blessing over the bread and wine, he would incense the gifts and the altar.  Traditionally, the prayer he says while incensing the gifts ask of God that as our prayer rises with the incense, that He descend upon us.

He then offers the incense to the altar, like St. Raphael and the Archangels who present the prayers of the people through the incense presented to the altar of God in Heaven.  So too, does the priest carry the offerings of the people, that they may rise like the sweet aroma of incense and be acceptable to God our Father.