Circle of Life

"Circle of Life" was a song from The Lion King accidentally quoted by the Tenth Doctor when discussing humanity's potential. The lyrics he quoted were:
 * ''From the day they arrived on the planet
 * ''And, blinking, stepped into the sun.
 * ''There is more to see, than can ever be seen
 * ''More to do than—

(TV: The Christmas Invasion)

Behind the scenes

 * Elton John sings the original version of the song. The song title does not get a mention on-screen. The original lyrics are actually slightly different to the ones quoted by the Doctor — the first line is, "From the day we arrive on the planet", not "they arrive".