11 Do you understand already the Mysteries of the Apostle's Faith? Do you think to know Christ already? Tell me, then, Who is it Who strips from Himself His flesh, and what is that flesh stripped off? I see two thoughts expressed by the Apostle, the flesh stripped off, and Him Who strips it off: and then I hear of Christ raised from the dead by the working of God. If it is Christ Who is raised from the dead, and God Who raises Him; Who, pray, strips from Himself the flesh?
Who raises Christ from the dead, and quickens us with Him? If the dead Christ be not the same as the flesh stripped off, tell me the name of the flesh stripped off, and expound me the nature of Him Who strips it off. I find that Christ the God, Who was raised from the dead, is the same as He Who stripped from Himself His flesh, and that flesh, the same as Christ Who was raised from the dead; then I see Him holding principalities and powers up to show, and triumphing in Himself.
Do you understand this triumphing in Himself? Do you perceive that the flesh stripped off, and He Who strips it off, are not different from one another? He triumphs in Himself, that is in that flesh which He stripped from Himself. Do you see that thus are proclaimed His humanity and His divinity, that death is attributed to the man, and the quickening of the flesh to the God, though He Who dies and He Who raises the dead to life are not two, but one Person? The flesh stripped off is the dead Christ: He Who raises Christ from the dead is the same Christ Who stripped from Himself the flesh.
See His divine nature in the power to raise again, and recognise in His death the dispensation of His manhood. And though either function is performed by its proper nature, yet remember that He Who died, and raised to life, was one, Christ Jesus.
Source: On the Trinity (New Advent)