Censer

From Rationale Divinorum Officiorum: 

"Incense is burned, which signifies the devotion of prayer, or one who has the seven gifts of the Holy Spirit, who, being assimilated to God, can offer Him a devout prayer, whose image he is... This frequent use of incense is the continual dialogue between Christ the priest and pontiff and God the Father, done on our behalf... The copious burning of incense in the corners and in the middle of the altar is the multiplication of prayers in Jerusalem and in the universal Church."[1] 

The censer is a vessel for prayer, facilitating or representing communication with God. 

---

[1] Durand, Guillaume, and Thibodeau, T. M. The Rationale Divinorum Officiorum of William Durand of Mende : (a New Translation of the Prologue and Book One). Records of Western Civilization. New York: Columbia University Press, 2007, 87.