The Blessed Virgin Mary asks the Archangel Gabriel, "How can this be, since I have no relations with a man?" (Personally, I prefer the earlier, more literal translation, "since I have not known man." The new, "modern" version is much more clinicial in its phrasing of so delicate and personal a matter.) Those of us who are amateur theologians may note the evident similarity of her bold question to Zechariah's query, "How shall I know this? For I am an old man, and my wife is advanced in years." There is a crucial difference, however, in the purposes of these questions.
Zechariah wanted to "test the spirit." When he says, "How shall I know this?" he means "How shall I know that what you are saying to me is true?" Gabriel is justifiably put off by this, since Zechariah was undoubtedly infused with the knowledge of the authenticity of Gabriel as the Lord's personal messenger. This is quite different from Mary's question, "How can this be?" for she is concerned, not about the truth of the prophesy, but about how it will come about. She asks so that she might be prepared for cooperation. Zechariah asks in order to be sure that he should cooperate at all. Zechariah's main cooperation, apart from continuing his "relations" with his wife, will be to announce the baby's arrival and to teach the boy as he grows up. Gabriel takes away his power of speech so that he might appreciate the importance God places on the cooperation of that power as well as to appreciate how sinfully he used it in questioning Gabriel.
Mary models cooperation with God for us. When we receive a calling, and if it unmistakeably comes from God, our job is to ask not, "Must I jump?" but "How high?" and "How do I prepare to jump so high, or will this be a miracle?"
Gabriel's answer gets to the heart of her question, even though we don't really understand what it means, exactly. "The Holy Spirit will come upon you, and the power of the Most High will overshadow you." If you've never experienced anything like this, you can't possibly know what it means, other than "Don't worry, God will take care of the details."
There is, however, an important allusion in Gabriel's phrasing to how a male has "relations" with a female. There is also an echo of this in a biblical miracle where the prophet Elijah brings the son of the widow of Zarephath back to life. [See 1 Kings 17:17-24] It speaks of a life-giving action, and is further indication of how God views the sacred character of "relations."
By comparison to Mary's total openness, and eagerness to be ready to do the Lord's will, Zechariah's response is a "Why bother?" All of us are guilty of this reluctance to invest in fulfilling God's will. What priority do we even give to celebration of the Mass in our lives, or to reconciliation with God and the community through frequent confession? What priority do we give to learning the teachings of Scripture, Tradition and the Magisterium? What priority do we give to preparing to fulfill our vocation in life, whether it be marriage, the priesthood, religious life or lay service in celibacy? What priority do we give to daily prayer and getting to know and understand God's will for us?
Zechariah's final word to Gabriel was, "How shall I know this? For I am an old man, and my wife is advanced in years." His was a voice full of skepticism. Mary's final word was full of humble acceptance of God's will, "Behold, I am the handmaid of the Lord. May it be done to me according to your word." It is impossible to imagine how much this must have pleased God!
If we had Mary's openness to receive grace, what might we not do to please God?