She Walks in Beauty by Lord Byron.
The speaker compares a beautiful woman—who is walking—to a clear night sky full of bright stars. The finest light and darkness come together in harmony in this woman's appearance, particularly within her eyes. This gentle and delicate play of light is heavenly—indeed, heaven usually refuses to grant this supernatural light to the showy daytime.
A touch more shade or even one ray of light would have greatly diminished the woman's beauty. This beauty, which is hard to put into words, shows itself in every strand of the woman's hair, and gently falls on her face. Her sweet, angelic emotions play out on her face, revealing how pure and precious this woman is.
On the woman's cheek and forehead—softly and calmly, but noticeably—appear winning smiles and a glowing skin tone. These features reveal that the woman spends her days virtuously, that she possesses a peaceful mind, and that she has an innocent, loving heart.