One of the important differences between a romance and a novel is that the former may, although not necessarily, operate on the allegorical level. Since the characters in an allegory represent rather fixed or secure ideas, they do not have to undergo change; they can therefore remain basically the same throughout the whole story. On the other hand, a character fully developed within the context of the action and the other players is able to move about with more ease because he is not the symbol of some pre-determined concept from which he cannot vary. Nearly all critics of Green Mansions have commented upon Hudson's lack of extensive characterization in the romance, but Hudson, writing an allegory, is depicting within the text the interplay of ideas so that the criticism seems unfair in view of the author's plan.
The selection of one of the most primitive and unknown areas of South America is no accident on Hudson's part because such a choice illustrates emphatically, though in exaggerated manner, the idea of nature; Hudson wrote often of the beauties of the English countryside and disliked intensely the large population centers, such as London, but England was probably too intimately associated with civilization to serve his purpose. The jungle and hinterland, first visited by Abel, symbolize the wild, untamed nature which humanity has forgotten or ignored in its flight to the cities. Civilization has divorced humanity from its roots in the outdoors, and we are now alienated psychologically from a needed source of inspiration and idealism. The "green mansions," set within the framework of the vastness of primitive nature, represent an Eden or lost paradise. This allegorical mode occurs, therefore, beyond the boundaries of civilized forces; there are no crowds and no preoccupation with the myriad problems of cities. The romance could be set in almost any chronological period after the conquest of the South American continent by the Spanish.
Into this situation Hudson settles comfortably as he proceeds to develop the idea of Abel and the idealization of Rima. The human race is portrayed in the anguished searching and inquiry of Abel; the disillusioned acceptance of reality by Nuflo; and the combination of primitive simplicity and happiness by Rima. Rima, indeed, is the dream of humanity, and Abel symbolizes the possibility — but not probability-of transferring that vision to the mass of humanity. Nature is, of course, brooding over the whole scene and action as the great imponderable force, for good and for evil. Abel is also the epitome of the man of Hudson's time, and he is the literary expression of the author's observations and conclusions about civilized influences from lengthy English residence. Likewise, Abel is the symbol of the romantic, sensitive, and cultured individual who could appreciate nature. In the involvement of this trio — the "green mansions," Abel, and Rima — is drawn the allegory of Hudson: nature, humanity, and ideal.