For all the contradiction of the present-day world, for all the diversity of social and political systems in it, and for all the different choices made by the nations in different times, this world is never-the-less one whole. We are all passengers aboard one ship, the Earth, and we must not allow it to be wrecked. There will be no second Noah's Ark.
-Mikhail Gorbachev, Perestroika (1987, p. 12)