Who is "Luna" in Byron's "To Mary, On Receiving Her Picture"?

Question

Here are the fourth and fifth stanzas of "To Mary, On Receiving Her Picture" by Lord Byron:

Here, I behold its beauteous hue;
    But where's the beam so sweetly straying,
Which gave a lustre to its blue,
    Like Luna o'er the ocean playing?

Sweet copy! far more dear to me,
    Lifeless, unfeeling as thou art,
Than all the living forms could be,
    Save her who plac'd thee next my heart.

1. In the fourth stanza, Byron mentions the blue eyes of his beloved. He asks where is the beam of her eyes sweetly wandering? Then he says, "Like Luna o'er the ocean playing". What does "Luna" mean?

2. In the fifth stanza, he says that the copy of her picture is even more dearer to him. Then he says, "Lifeless, unfeeling as thou art". Does it mean that the painting is lifeless and dull, for Mary might have been lively and vivacious as a person or does it mean that Mary is lifeless and unfeeling just an inanimate object such as a painting is? Then he says, "Than all the living forms could be, Save her who plac'd thee next my heart." What could it possibly mean?

Answer 1

Luna is another name for the Moon. Most celestial bodies have a fixed name, but "the" moon is an oddity in that regard.

As it turns out, the Moon did have other names, notable among them, and in keeping with the naming schema of other local celestial bodies, was one taken from the name of an ancient and powerful deity- Luna, the Roman Goddess of the Moon.

Latin in origin, the word “Luna” is still very much associated with the Moon (as is “Selene”, to a lesser extent, the Greek Moon goddess). For instance, “Luna” is noted as being the root of words like “lunar”. However, “Luna” as a name for the Moon is still pre-dated by early derivatives of the word moon.

From How the Moon Got Its Name. Also verified by Wikipedia.

The verse in the fifth stanza reads oddly because Byron has subverted the natural-language order to make things rhyme. To break it down:

• The "sweet copy" is "lifeless and unfeeling".
• Yet it is "far more dear" than "all living forms"
• Except for the one living form ("Save her", here shorthand for "save for her" an archaic phrasing of 'except for her') that put the picture next to his heart.

Or, using Byron's language in a clearer sequence:

Sweet copy!
Lifeless, unfeeling as thou art,
[you are] far more dear to me,
Than all the living forms could be,
[Except for] her who plac'd thee next my heart.

In short, then, Byron values the portrait above any other human being, except for the person, Mary, who gave it to him.