Mary's "Yes"

Be that as it may, by exalting our Lady as man’s yes to God, as the obedient servant of the Lord, as the human temple of the Logos, the Church underscores the active role that humanity plays in the drama of salvation. The Virgin is, in a very literal sense, the stand-in for all of humanity. It is she who utters, on our behalf, the fiat: “Let it be unto me according to my word.”
But, you ask, does this not impinge upon the uniqueness of Christ and his work? Only if you have a Nestorian Christology. The Virgin Mary is the one human who cooperates completely and fully with God. It is she who undoes the disobedience of Eve by her obedience. Remember, I said a couple of weeks ago that the only sense that an Orthodox Christian can speak about human progress is the progress from Eve to our Lady. The Virgin is the apex of human progress. And yet, there is a limit even to what a perfectly obedient human can do. Mary could and did say yes to God in the most perfect way possible, but that yes by itself could not save man from death. She herself died. Only God, God made flesh, a crucified God, as the Fathers put it, could destroy death from the inside and make a path for all to the resurrection from the dead.

So we see that the Orthodox veneration of the Virgin Mary is necessary to preserve both the uniqueness of Christ, that is, the God-man’s work of salvation, while at the same time preserving the absolute necessity of human cooperation with God. Christ is our one and only Savior, but Mary is our role model. More than that, Mary sums up what it means to be truly human. That is why the liturgical year begins with her birth and ends with her death and translation.

Thanks to source:
http://www.ancientfaith.com/podcasts/carlton/the_marian_necessity