Here, ladies and gentlemen, is mariology in one lesson:
It was a deed of perfect justice that our nature, which was voluntarily enslaved and struck down, should again enter the struggle for victory and cast off its voluntary enslavement. Therefore, God deigned to receive our nature from us, hypostatically uniting with it in a marvellous way. But it was impossible to unite that Most High Nature, Whose purity is incomprehensible for human reason, to a sinful nature before it had been purified. Therefore, for the conception and birth of the Bestower of purity, a perfectly spotless and Most Pure Virgin was required.
Today we celebrate the memory of those things that contributed, if only once, to the Incarnation. He Who is God by nature, the Co-unoriginate and Coeternal Word and Son of the Transcendent Father, becomes the Son of Man, the Son of the Ever-Virgin. "Jesus Christ the same yesterday and today, and forever" (Heb. 13:8), immutable in His divinity and blameless in His humanity, He alone, as the Prophet Isaiah prophesied, "practiced no iniquity, nor deceit with His lips" (Is. 53: 9). He alone was not brought forth in iniquity, nor was He conceived in sin, in contrast to what the Prophet David says concerning himself and every other man (Ps. 50/51: 5). Even in what He assumes, He is perfectly pure and has no need to be cleansed Himself. But for our sake, He accepted purification, suffering, death and resurrection, that He might transmit them to us.
God is born of the spotless and Holy Virgin, or better to say, of the Most Pure and All-Holy Virgin. She is above every fleshly defilement, and even above every impure thought. Her conceiving resulted not from fleshly lust, but by the overshadowing of the Most Holy Spirit. Such desire being utterly alien to Her, it is through prayer and spiritual readiness that She declared to the angel: "Behold the handmaiden of the Lord; be it unto Me according to thy word" (Lk. 1:38), and that She conceived and gave birth. So, in order to render the Virgin worthy of this sublime purpose, God marked this ever-virgin Daughter now praised by us, from before the ages, and from eternity, choosing Her from out of His elect.
Now, when Righteous Joachim and Anna saw that they had been granted their wish, and that the divine promise to them was realized in fact, then they on their part, as true lovers of God, hastened to fulfill their vow given to God as soon as the child had been weaned from milk. They have now led this truly sanctified child of God, now the Mother of God, this Virgin into the Temple of God. And She, being filled with Divine gifts even at such a tender age, ... She, rather than others, determined what was being done over Her. In Her manner She showed that She was not so much presented into the Temple, but that She Herself entered into the service of God of her own accord, as if she had wings, striving towards this sacred and divine love. She considered it desirable and fitting that she should enter into the Temple and dwell in the Holy of Holies.
Its quite wonderful, isn't it!