Gary K. Wolfe ... the intellectual basis of much science fiction---this kind of dialectical extrapolation---is more closely related to the emotional basis (the "sense of wonder") than is generally suspected. The process may be summarized somewhat as follows: the known exists in opposition to the unknown, with a barrier of some sort separating them. The barrier is crossed, and the unknown creates the known. But the crossing of the barrier reveals new problems, and this sets the stage for a further opposition of known and unknown. This barrier is crossed, yet another opposition is set up, and so on. The "sense of wonder" grows in part out of the tension generated by awareness of this opposition, and the images of the sense of wonder are those which most strongly reinforce this tension, images that stand at the barrier. The transformation continue until an opposition is arrived at that requires no further transformation or resolution.