Perhaps even to speak at length on this is a sign of extreme folly. The excess of abasement expressed in these words compels even the blasphemers of the Godhead to apply nothing of the kind to the Godhead.
The Godhead permitted the humanity to endure this, in order to teach us that God the Word truly became man and assumed human nature. The mystery of the divine economy was accomplished neither in fantasy nor in appearance.
For even with all this, Simon, Menander, Cerdo, Marcion, Valentinus, Basilides, Bardesanes, and Manes taught their followers that Christ had no human nature at all.
Clearly, an even greater number of people would have fallen into this error if He had not endured human infirmities, apart from sin.
By "the days of His flesh," the Apostle means the time of mortality, that is, the time when Christ had a mortal body.
He speaks of the prayer which Christ prayed before the Passion, saying, "Father, if it is possible, let this cup pass from Me" (Mt 26:39).
The Apostle spoke in an intensified manner when he said, "He learned obedience through what He suffered." Christ showed obedience not after the suffering, but before the suffering.
By perfection he means the Resurrection and immortality, for this is the goal of the divine economy.
He presented all the sufferings in an intensified way, not only to prove the truth of the Incarnation, but also to confirm the word he had already spoken.
"For we do not have a High Priest who cannot sympathize with our infirmities, but One who in every respect has been tempted as we are, yet without sin."
Thus he also persuades those to whom he wrote to remain in the faith and boldly trust in the compassion and love for mankind of this High Priest.
[...] we find that He often prays and bends the knee. The Apostle clearly teaches that this belongs to human nature, not to the Godhead, which is in need of nothing.
He says in the Epistle to the Hebrews: "In the days of His flesh, He offered up prayers and supplications, with loud crying and tears, to Him Who was able to save Him from death."
"And He was heard because of His reverence. Though He was a Son, He learned obedience through what He suffered. And having been made perfect, He became the cause of eternal salvation to all who obey Him" (Heb 5:7-9).
It was not God the Word Who was made perfect, for He is perfect before the ages. Rather, it was the form of a servant, made dispassionate, incorruptible, and immortal.
Therefore the Apostle said that the Lord accomplished this "in the days of His flesh," when He had a mortal body. All this belongs to the humanity, not to the Godhead.
The Godhead permitted the humanity to endure this, in order to teach us that God the Word truly became man and assumed human nature. The mystery of the divine economy was accomplished neither in fantasy nor in appearance.
THEOSIS