CAPG's Blog 

St. Cyril of Jerusalem teaches that Christ was Priest before all ages,
 anointed by the Father in His eternal generation, so that His Priesthood 
had not its beginning in time, but is immutable. This Priesthood consisted
 not in humiliations, in sufferings, in prayers, but in knowing the Father,
 in acknowledging Him as the source of the Godhead, and Himself as true God 
of true God. It consisted (according to St. Thomas) in saying to Him,
 "Thou art my Father," " I am in Thee, and Thou in Me; I love Thee and honor
 Thee with an infinite love and infinite glory; for infinite is the love 
which Thou bearest Me, and infinite the glory which Thou hast communicated to Me." 

He united this Priesthood with His temporal Priesthood when He assumed human nature;
taking from us (as St. Augustin says) that which 
He would offer for us. The Word (says St. Ambrose) appeared clothed with flesh, in His 
dignity of King and of Judge, and full of sacerdotal justice. Our guilt could not be 
cancelled without a sacrifice, and therein a sacrifice was sought. The Son (says St. Gregory)
took our nature, but not our sin, and offered Himself a sinless Victim. His Incarnation 
was itself a Sacrifice which lasted His whole mortal life, was consummated upon the Cross,
and is continued in glory at the Right Hand of the Father, and on our altars on earth.
In the womb of Mary (says Dionysius of Alexandria) the King of Glory was made a High 
Priest; and He continueth such for ever, now that He has entered once into the Holies,
having obtained eternal redemption.

 Let us adore our great High Priest, in Whose hands is our salvation. 

Source: Meditations For the use of the Clergy, Oblates of St. Charles