Added to the structural complexity is the variety in Balzac's treatment of his subject matter. We shall distinguish between realistic, naturalistic, and romantic or subjective approaches.
Le Père Goriot has been acclaimed, and justly so, as a great realistic novel. Balzac was concerned all his life with getting data on his characters; he went as far as visiting graveyards and jotting down the names on the tombstones. He studies the society of his time and gives us in his book invaluable information about the members, their interests, their behavior. He depicts many levels of social classes, high aristocracy, the middle world, the bourgeois, and the picturesque and somewhat pitiful members of the lower classes: Bianchon, old Poiret, Mlle. Michonneau, Gobseck the usurer, Sylvie, and Christophe.
Balzac's realism is also apparent in the minute descriptions he gives us, in the way he makes his characters express themselves according to their background (for example, Christophe and Sylvie, Mme. Vauquer, the Duchess de Langeais).
But Balzac goes beyond realism. He assesses each human being, classifying him as an entomologist or a zoologist would, comparing each one of his characters in the book with an animal of some kind. He tries to show us that man is predetermined not so much by his psychological makeup but rather by his environment, his social milieu. This scientific or pseudo-scientific approach to human reality constitutes the naturalistic elements in the novel.
Although Balzac has taken so much care to present his characters objectively, in an objective situation, the novel is filled with subjectivity.
We read lengthy dissertations and short remarks which obviously expound Balzac's ideas and not those of the characters (even in the pathetic delirium of Père Goriot, we can feel Balzac's interference). And if it would be foolish to say that such-and-such character is Balzac, thereby denying this great writer the gift of creativity, we still find many traits of the author in Rastignac and in Vautrin, and his own preoccupations with money, love, and success.