Lady, I thank thee for thy loveliness,
Because my lady is more lovely still.
Glorying I gaze, and yield with glad goodwill
To thee thy tribute; by whose sweet-spun dress
Of delicate life Love labours to assess
My lady's absolute queendom; saying, “Lo!
How high this beauty is, which yet doth show
But as that beauty's sovereign votaress.”
Lady, I saw thee with her, side by side;
And as, when night's fair fires their queen surround,
An emulous star too near the moon will ride,—
Even so thy rays within her luminous bound
Were traced no more; and by the light so drown'd,
Lady, not thou but she was glorified.

Dante Gabriel Rossetti

http://www.poemhunter.com/poem/sonnet-xxix-the-moonstar/