Lem’s story is dual: It deals with the relationship between Kelvin and his visitor at the same time that it unfolds the many philosophical implications of the attempt to make contact with the mind of the ocean. Lem’s thesis is that all attempts to define reality, on earth or in space, are inevitably anthropocentric. An author of one of the books in Solarian studies maintains that all scientific achievements reveal the projection of anthropomorphic definitions on all reality. As a result, genuine contact between humans and a nonhuman intelligence or civilization is, by definition, impossible. Snow tells Kelvin that all space travel is nothing more than the attempt to define the entire cosmos in the terms of Earth: “We are only seeking Man.... We don’t know what to do with other worlds. A single world, our own, suffices us; but we can’t accept it for what it is.”
This idea is repeated in a passage which relates the cosmic implications of Lem’s thesis to the relationship between Kelvin and “Rheya”: “Man has gone out to explore other worlds and other civilizations without having explored his own labyrinth of dark passages and secret chambers, and without finding what lies behind doorways that he himself has sealed.” In other words, at the same time that human beings impose human definitions on the rest of the universe, they neglect to take account of their own human nature. They thus fail to understand both the universe without and the universe within.
Lem’s theme, therefore, in spite of his condemnation of this double human failure, is emphatically humanist. That human knowledge is burdened with limitations does not mean that humans should not use that knowledge to explore to the fullest the human condition here on earth, both the inner world of the mind and emotions and the external moral world of social and personal relations.
Finally, the novel suggests a theological implication of the human encounter with Solaris. Kelvin defines for Snow an imperfect and even sick god, a god whose power and knowledge are limited and who thus creates horror: a god, like the ocean, who simply exists. For Kelvin, this would explain the inability to make contact with the ocean. If it is like the god he has hypothesized, its creation of the visitors has been to no purpose, neither benign nor evil. This notion also supports Lem’s thesis that the acquisition of human knowledge is hopelessly flawed and leads inevitably to tragedy. If the god of the cosmos is like the ocean, then the attempt to make contact with it is doomed and subject to the experience of its “cruel miracles.” The only appropriate effort is the exploration of human psychology, the improvement of relations between individuals and societies, and the maintenance of sane and healthy life on earth.