The main character of Last and First Men is human nature. The narrator speaks as one of a species which has realized human nature to the fullest in his time. He speaks to the first men, who can hardly imagine what such humanity may be. Though many thematic issues are explored, the main subject is always the possibilities inherent in human consciousness, how they might be meaningfully and beautifully organized.
Stapledon sees human nature as divided between the individual passions that arise from the need for personal survival and group passions that arise from the need for species survival, between physical and emotional being on one hand and self-consciousness and the need to understand on the other, and between subjectivity and objectivity. The various species he presents illustrate the permutations of imbalances and balances among these main potentials. The eighteenth men represent an ideal manifestation of humanity because they have found a proper balance of these possibilities.
A proper balance includes a complete subordination of the individual to the race without the surrender of the individual. This seemingly impossible balance becomes possible only when telepathic communication allows a perfect understanding between individuals. It approaches the ideal on Neptune, where “families” of ninety-six members frequently experience complete mental union and where occasionally the whole race experiences such union. All these types of union depend upon the physical bonds of emotion and affection that these people cultivate. The regular experiences of “higher consciousness,” or group mind, lead to a blending of objectivity and subjectivity that the narrator often characterizes as aesthetic and tragic.
Last men are able to look upon the entire history of humanity as a work of art, the expression of a cosmos that may be alive and purposefully attempting to achieve consciousness. The last men are able to accept humanity’s failures and its ultimate defeat in time, for even if the cosmos achieves consciousness, it must end. To see and accept the beauty of this effort in the face of ultimate defeat the narrator characterizes as tragic nobility. This is the sort of “character” the narrator gives humanity. His narrative becomes the record of humanity’s often blind and blundering reaching out in the direction of spiritual fulfillment.