John Chrysostom

"For it was the good pleasure of the Father, that in Him should all the fullness dwell."

Whatsoever things are of the Father, these he saith are of the Son also, and that with more of intensity, because that He both became "dead" for, and united Himself to us. He said, "Firstfruits," as of fruits. He said not "Resurrection," but "Firstfruits," showing that He hath sanctified us all, and offered us, as it were, a sacrifice. The term "fullness" some use of the Godhead, like as John said, "Of His fullness have all we received." That is, whatever was the Son, the whole Son dwelt there, not a sort of energy, but a Substance.

He hath no cause to assign but the will of God: for this is the import of, "it was the good pleasure...in Him."