“Humans make the mistake of believing that it is their right to survive. Species die out on this planet all the time without anyone noticing. The planet will still be there, and we must lose this attitude of divine right, that something will save us...”

“We have a responsibility toward the other life-forms of our planet whose continued existence is threatened by the thoughtless behavior of our own human species. . . . Environmental responsibility – for if there is no God, then, obviously, it is up to us to put things right.”

“The Doctor: The Fourth Great and Bountiful Human Empire. And there it is: planet Earth at its height. Covered with megacities, five moons, population 96 billion. The hub of a galactic domain, stretching across a million planets, a million species. With mankind right in the middle.[Adam faints]The Doctor: [leans towards Rose, still looking out over the Earth] He's your boyfriend.”

“This planet is dying. The human rase is killing it. ...If the Earth dies, you die. If you die, the Earth survives.”

“The planet has survived everything, in its time. It will certainly survive us.”

“People from a planet without flowers would think we must be mad with joy the whole time to have such things about us.”