On his way back to the boardinghouse, Eugène is reflecting about his evening. As he has been seen in public with his cousin and Mme. de Nucingen, Paris society's tightly closed doors will open for him, even possibly Mme. de Restaud's. Perhaps he can win pretty Delphine's love and make a fortune with the help of her banker husband.
Upon arriving at the boardinghouse, Eugène goes up to see Old Goriot and reports on his evening, adding that he prefers Delphine because she seems fonder of her father. The two men then engage in a long conversation in which Goriot expounds on paternal love, saying, "since I have been a father, I have come to understand God." The old man adds that he would be so pleased if Eugène and Delphine were to love each other. Eugène, very touched by Goriot's concern and dismayed at Delphine's thoughtlessness, bids the old man goodnight.
This incident marks the beginning of a growing friendship between Rastignac and Goriot. The next day at breakfast, Goriot sits by Eugène, interested only in the young man's words and reactions. Eugène, stared at by Vautrin and recalling their previous discussion, feels uneasy and cannot avoid glancing at Victorine, the prospective heiress. But Eugène hopes that "his extemporized passion for Mme. de Nucingen . . . would preserve him from this temptation." Vautrin, though, continues to tempt him, saying that one should not go halfway but have "all or nothing."
The young man spends the rest of the day strolling aimlessly about and thinking of success, fortune, and of Vautrin's commentary on society. In the Luxembourg Gardens, he meets Bianchon, tries to explain his frame of mind, and asks for advice. The young medical student tells him that happiness is to be found inside, that it is not based on materialistic values; then, changing the subject, he mentions that he just saw Mlle. Michonneau and Old Poiret talking to a man who might well be a policeman in disguise and that he wants to investigate the couple further.
The theme of paternal love, predominant in this section, is one of the important components of the book and completes the entanglement of Goriot and Eugène.
Goriot, in a very touching scene, explains to Eugène his love for his daughters. He shows us, at the same time, the sublime and the extreme elements in his passion. He says:
Well then, since I have been a father, I have come to understand God. He is everywhere in the world, because the whole world comes from Him. And it is just the same with my children, monsieur. Only I love my daughters better than God loves the world, for the world is not so beautiful as God Himself is, but my children are more beautiful than I am. Their lives are so bound up with mine that I felt somehow that you would see them this evening.
Some of what he says expresses not only pure paternal love but also involves the pure act of creation. This was a subject dear to Balzac, who felt that an author is also a creator and that there is the same relationship between a child and his parents as between a writer and his works: "Are not our finer feelings the poem of the human will?"
Developed parallel with the above is the atmosphere of social corruption in which Eugène finds himself more and more deeply immersed. He is shocked at Delphine's lack of concern for her father. But, at the same time, he enjoys the glamour of all the receptions and starts coldly speculating on how he can conquer Delphine and make a fortune with the help of her husband — and there is still Vautrin's offer. We notice, though, that Eugène is still trying to fight his "wicked impulses," but now he needs the help of his friend Bianchon.
And the detective story, which will culminate in the next part, moves along. Bianchon has noticed the suspicious behavior of Old Poiret and Mlle. Michonneau in conversation with a man who looked "like a detective dressed up like a decent retired tradesman."