This commentary is based on my notes after reading The New International Commentary on the Old Testament: Song of Songs, by Tremper Longman III, 2001
Poem 21 (Ch 8)
(Caring for Each Other’s Family)
v 8 Our sister is small,
and she has no breasts,
What should we do for our sister
on the day she is spoken for?
v 9 If she is a wall, we will build a silver battlement for her.
But if she is a door, we will enclose her with a cedar board.
There is a sister. Since the woman was not properly cared for, it can be assumed that her sister is not either. The man is taking responsibility for her. If she is shy, lacking confidence, he will adorn her with strength. If she is permiscuous, naive, undiscerning- trusting and letting everyone in, he will keep guard her closely.
v 10 I am a wall, and my breasts are like towers,
Thus I will be in his eyes like one who brings peace.
The woman’s presence in his life is one of strength, protection and peace. That she is a ‘wall’ indicates that she will not open herself to anyone but him.