She is as in a field a silken tent
At midday when the sunny summer breeze
Has dried the dew and all its ropes relent,
So that in guys it gently sways at ease,
And its supporting central cedar pole,
That is its pinnacle to heavenward
And signifies the sureness of the soul,
Seems to owe naught to any single cord,
But strictly held by none, is loosely bound
By countless silken ties of love and thought
To every thing on earth the compass round,
And only by one's going slightly taut
In the capriciousness of summer air
Is of the slightest bondage made aware.
There is a tension here. The freedom within constraint is a repeated theme; a foundation of Frost’s poetry. In his poem  Tree at my Window  the tree strains to come in and the speaker wants to go out. This idea appears again in  Mending Wall , the idea of coming together in order to stay apart. 
 This tension is beautifully expressed in the concise form of the sonnet.
The Silken Tent