By his sufferings in the garden and upon the cross the Lord Jesus was made perfect. But what perfection was this? It clearly does not mean that by these sufferings in the garden and upon the cross our Lord was made perfect as the Son of God, nor perfect as the Son of man, for he was perfect before as possessing infinite perfection in his eternal Godhead, and was endued also with every possible perfection of which his sacred humanity was capable. He needed no perfection to be added to his Godhead; it was not susceptible of it; no perfection to be added to his manhood, for it was "a holy thing" in union with eternal Deity. But he needed to be made perfect as a High Priest.
It was through his sufferings that he was consecrated or dedicated in an especial manner to the priesthood, for this corresponds with his own words: "And for their sakes I sanctify myself" (John 17:19); that is, I consecrate or dedicate myself to be their High Priest. The two main offices of the high priest were to offer sacrifice and make intercession. Sacrifice came first; and the sufferings of our Lord in the garden and upon the cross were a part of this sacrifice. He was therefore "made perfect through suffering," that is, through his sufferings, blood-shedding, and death he was consecrated to perform that other branch of the priestly office which he now executes.
Thus as Aaron was consecrated by the sacrifice of a bullock and a ram, of which the blood was not only poured out at the bottom of the altar and sprinkled upon it, but put also on his right ear and hand and foot, so was his great and glorious Anti-type consecrated through his own sacrifice and blood-shedding on the cross; and thus being made perfect, or rather, as the word literally means, being perfected, he became the author of eternal salvation unto all them that obey him.