One of my favorite melodies is the "Swan theme" from Tchaikovsky's Swan Lake. I'm wondering what are the lyrics to this theme, and where they came from. I know, of course, that Tchaikovsky was Russian, but it's a fragment of German lyrics that comes to my mind:

"Seht, wie die wilden Schwanen ziehen, hinaus in blauen Firmament."

Googling isn't helping me. Can somebody give me lyrics for this beautiful theme?
Thanks.

Instrumental recording: https://www.youtube.com/watch?v=9cNQFB0TDfY