In Star Trek, Roddenberry made a universe where known must be brought into contact with the unknown, where drama is played out on the borderline between self-definition and self-annihilation. The great enterprise at stake is dramatizing our own encounters with the unknown and hence with the alien within ourselves, as well as the alien beyond. It is an evolutionary process like life.

Also, as in life, this process of encountering the unknown involves us with both the familiarity of the past and the foreignness of the future…. Spock the hybrid Vulcan-human can function as resident alien precisely because he is half human and can therefore dramatize the point of contact between the familiar and the foreign. Spock's foreignness, on the other hand, allows us to see—worked out in him and hence in ourselves—the relation between polarities usually seen as diametrically opposed in our human world…. Such...