The Complement of Christ's Humanity

The first Eve was taken out of Adam: she was a person who, at the moment of her creation by God, took unto herself the nature of Adam, to be his complement. We find an inverse relationship in the case of the New Eve: through her the Son of God became the "Last Adam", by taking onto Himself human nature. Adam was before Eve; the Last Adam was after the New Eve. However we cannot say that the humanity assumed by Christ in the womb of the Holy Virgin was a complement of the humanity of his Mother. It is, in fact, the humanity of a divine Person, that of the "man of heaven" (1 Corinthians 15:47,48). The human nature of the Mother of God belongs to a created person, who is the offspring of the "man of earth". It is not the Mother of God, but her Son, who is the head of the new humanity, "the head over all things for the Church, which is his body" (Ephesians 1:22-23). The Church is the complement of his humanity. Therefore it is through her Son, and in His Church, that the Mother of God could attain the perfection reserved for those who bear the image of the "man of heaven".

from Vladimir Lossky In the Image and Likeness of God

"The Church is the complement of His humanity" - it is our humanity Christ assumed and in Him we are seated in Heaven; moreover the Church is also the complement of Christ's humanity, the fulfillment of His humanity as was foreshadowed by Eve's complement to Adam.