The incongruity between reality and appearance
The idea of subtext is a metaphor for the manner in which the European-American social circle in Europe misunderstands the true character of Daisy Miller. She is innocent and uncultured and incautious but the circle sees only the surface of her character and the actions that character takes. They imagine a member of their social circle, thus someone with the experience and knowledge to understand and exaggerate the mores and codes of the European culture, acting in the way that Daisy Miller does. They do not take the time to look beneath this pretense to find that she is naturally innocent, acting on impulse instead of caution and convention. She rebels not by having a great knowledge of the rules which bind the society and consciously deciding to throw them out the window, but by being limited in her scope of experience and by refusing to change her natural ways in order to please a culture to which she does not belong. She oversteps even these bounds but not in the manner for which she will be ridiculed and rejected by her compatriots. The great theme of the disparity between reality and appearance is at its greatest strength in the relationship between Winterbourne and Daisy because of the conflict which roars inside of Winterbourne regarding the appearance he cannot overcome and the reality he cannot accept. He constantly asks himself, should she know better? Yet he does not realize that she does not know better and will ruin herself because of it.
Knowledge as evil versus inexperience as innocence
James explores the type of an American girl who is innocent of the knowledge of evil and immorality. However, she is immersed in an environment of an elusive evil, concentrated in Rome and symbolized mainly in the dark foreshadowing of Daisy's ruin in the shadowed cavernous scene of the Colosseum. One better understands the hypocritical evil of the Euro-American social circle when they gossip about Daisy's behavior through vespers at St. Peters, symbolic of the evil of their experience and knowledge. Daisy's lack of knowledge and experience deceives Winterbourne who is incapable of seeing life through the lens of inexperience after leaving America. He thus fails to understand her inexperience as innocence.
Outward action versus inward meditation
This theme focuses on the problems of communication, especially in regards to the relationship between Daisy and Winterbourne, and the differences in types of character. Daisy is a character who reacts on impulse to the world around her and will say something or act without hesitation. Winterbourne, on the other hand, more representative of the European American circle, acts on pretense frequently and will often contain his feelings inwardly. He meditates on Daisy's character repeatedly, trying to decide how to view her, but usually overthinks the situation. Winterbourne attempts to apply the conventional rules he has accepted since leaving America to Daisy without realizing that she is not dissecting the world with the same meditating process that he undertakes.
Nature versus urbanity
A rather broad theme which acts as a vehicle to illustrate the conflicts between natural response and convention and social custom. Rousseau believed that natural man's innocence and purity was destroyed by the rigid rules of formalized civil society. By referring to the Golden Age in chapter four, the reader is reminded of the philosophic notions of nature's ruin at the hands of civilization. James is likely implying subtextually that Daisy's position in a sort of Golden Age is a state of innocence and goodness, not something to be insulted or ridiculed by characters such as Mrs. Costello. Daisy, as her name symbolizes, is simple and natural whereas her companion, the "beautiful Italian", is an imitation of a gentleman, urbane and artificial. The urbanity symbolized in the formal civilized setting of Rome overwhelms the natural innocence of Daisy and she succumbs to harsh condemnation, incaution, and a lack of love. Nature overcomes urbanity in the end, as Giovanelli confesses Daisy's innocence to Winterbourne.
