" After millennia of philosophical debate , the issue was settled decisively in favor of the plurality of worlds . They might be profoundly different from our planet . None of them might be as congenial for life . But the Earth was hardly the only one ... But by the nineteenth century , observational astronomy had made it clear that the Sun is but one lonely star in a great self-gravitating assemblage of suns called the Milky Way Galaxy . Far from being at the center of the Galaxy , our Sun with its entourage of dim and tiny planets lies in an undistinguished sector of an obscure spiral arm ... [ And today ], some modern deep sky photographs show more galaxies beyond the Milky Way than stars within the Milky Way . Every one of them is an island universe containing perhaps a hundred billion suns . Such an image is a profound sermon on humility ... We could not have known beforehand that the evidence would be , so repeatedly and thoroughly , incompatible with the proposition that human beings are at center stage in the Universe . But most of the debates have now been settled decisively in favor of a position that , however painful , can be encapsulated in a single sentence : We have not been given the lead in the cosmic drama . Perhaps someone else has -- Perhaps no one else has ... In either case , we have good reason for humility ." ~ Carl Sagan
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