This is Piano Sonata No. 14 in C-Sharp Minor, "Moonlight," by Beethoven. The first movement is incredibly popular among listeners and intermediate pianists. It seems simple at first, but requires a skilled hand to successfully wring out the meditative emotion. The third movement is famous for it's crazed emotional take on the original theme. The cheerful second movement is often forgotten in between the charged beginning and end. While the nickname "moonlight" was not given to the piece by Beethoven, it still remains an accurate descriptor.
"When I consider Your heavens, the work of Your fingers,
the moon and the stars, which You established—
what is man, that You are mindful of him?
And the son of man, that You care for him?" (Psalm 8:4-5 TLV)
In this verse, the moon and stars are used as examples of G-d's creative portfolio. If G-d created innumerable stars and the moon that controls the tides, then how much more do we, in His image, mean to Him?
The contemplative nature of the first movement matches these musings well. The third movement reflects the power and might of G-d (v. 3). The second conclusion is the conclusion of the psalm, verse 10: "Adonai our Lord, how excellent is Your Name over all the earth!"
Next time you stand in the moonlight, consider He that made the moon to reflect the sun reflects His glory in you on earth.