Chapter One. Once upon a time, and a very good time it was

There was a moo cow coming down along the road
So He came Himself in weakness not in power
And He sent thee, a creature in His stead
With a creature's comeliness and luster
Suited to our state
And now thy very face and form dear mother
Speak to us of the eternal;
Not like earthly beauty, dangerous to look upon
But like the morning star which is thy emblem
Bright and musical, breathing purity
Telling of Heaven and infusing peace
O harbinger of day! O light of the pilgrim!
Lead us still as thou hast led
In the dark night, across the bleak wilderness
Guide us on to our Lord Jesus, guide us home
Tower of Ivory?' they used to say, 'House of Gold?'

How could a woman be a tower of ivory or a house of gold?