From The General Instruction on the Roman Missal

308. Likewise, either on the altar or near it, there is to be a cross, with the figure of Christ crucified upon it, a cross clearly visible to the assembled people. It is desirable that such a cross should remain near the altar even outside of liturgical celebrations, so as to call to mind for the faithful the saving Passion of the Lord.

This is a homily delivered at Christ the Light Cathedral when Cordileone was Bishop of Oakland.  It is still crystal clear in its reasoning, and it may provide some insight in the whole debate on redefining Marriage. 

ARMS OF REV. FR. JEFFREY KEYES, C.PP.S.

Blazon: Azure, semée of plates, two keys or addorsed palewise, the wards to the chief, over all a cross fleury or; the shield ensigned with a priest’s gallero sable.

Motto: Omnia Christus est nobis.  (For us, Christ is Everything. —St. Ambrose)

Description: The azure (blue) field and or (gold) principal charges is chosen primarily in honor of the Virgin Mary, and in a secondary way as a reference to the seacoasts of California.  The keys, in the tradition of canting arms (which rely on visual puns), refer to the bearer’s last name, as well as also the Church at large, as well as the ministry of binding and loosing conferred on priests for use in the confessional.  As a symbol of the papacy they also obliquely recall St. Gregory and Gregorian Chant.   The cross is a direct reference to Christ, and the floriated ends, once again, recall His Mother.  The scattered plates (a heraldic term referring to all argent—silver or white—disks, irrespective of their actual significance) are an abstract representation of the descent of the manna on the Israelites and thus constitute a type of the Eucharist, recalling the bearer’s devotion to the sacred liturgy. 
                                                                                                                                                MATTHEW ALDERMAN