In this sonnet, the speaker compares the woman who is the subject to the poem to a silken tent. The theme or message the speaker wishes to convey through this metaphor is that the woman is, like a tent, tied to earth in a strong, but supple way that offers him a pleasurable security.
In the woman's case, rather than tied with ropes, she is bound to the earth by "countless silken ties of love and thought." This is a form of "bondage," but as with a tent, it is one of which the woman is hardly aware: her ties are not rigid but let air and breezes in.
The speaker's imagery conveys the beauty and groundedness of the woman. Her "soul," like the central beam of the tent, is "sure" and pointed toward the heavens. Like the tent, she "gently sways" amid ties that are loose, if solid. She is only aware of them, when like the tent in the breeze, a rope grows "taut" and tugs at her. In her case, we can imagine it to be the demand of a loved one pulling at her.
The speaker idealizes the woman he loves, using such lovely imagery as "silken" and "gently sways" to describe her. She provides shelter and security to him in a way that does not restrict, and yet he can rely on her to stay grounded and strong. It should be noted that we see her through his eyes and not as she might describe herself or her situation.