The chief engineer and the doctor together provide the novel's most succinct and explicit statement of theme: that the world is meaningless in itself, that value is a subjective quality assigned by man, and that such value is an illusion, a form of "self-flattery" and "vanity" that admittedly makes life possible ("makes the world go round"). Note that although the doctor appears to disagree with the chief engineer, he accepts the argument about material objects being worthless in themselves. What he objects to is the notion of "spiritual value," which he denounces as illusory, completing a picture in which neither the external nor internal worlds contain anything of real objective value.

There are some wonderful subtleties in this exchange. Note the introduction, "Upon my word," which contributes to the sense of "things" resting upon human assertion. Also note the connection between the doctor's swinging legs and the world going round, as if he is pedaling it, or rather, as if even his cynicism is a form of the "vanity" that supports the illusion of a physically turning world. See later where we are told that Monygham has "an ideal conception of his disgrace." Even the cynic is not free "for an instant" from the need for a dream-ideal.