Symbolism, Imagery, Allegory
Dolores Barbour is the name of the young woman in Spain that Frederick Hale plans on marrying. She's not mentioned much in the book, but you can tell that Frederick is in love with her by the way he cherishes a lock of her hair that he always keeps with him. We first see the hair when he holds up "a pocket-book, out of which fell a long lock of black hair, the sight of which caused Frederick's eyes to glow with pleasure" (2.6.72). Immediately, Frederick asks Margaret to tell him how beautiful the lock of hair is.
On second thought, Frederick dismisses the hair and says that it could never compare to Dolores herself. He says, "She is too perfect to be known by fragments. No mean brick shall be a specimen of the building of my palace" (2.6.73). In other words, he's not satisfied with judging Dolores by her different parts. Instead, he insists that you can only really know her true value if you meet her in person.
Huh. How about that. Frederick, having had a bit of a rough road, realizes that you can't "(know people) by fragments." Later, when Margaret's life has gotten way drama-filled and bumpy, she realizes as well that she can't know people by fragments. You know, like a certain John Thornton, who she believes she has known because of certain (jerky) fragments of his personality. Pride is dumb, Margaret.
Sometimes a cigar is just a cigar, and sometimes a lock of hair is just a lock of hair. Ha! Fooled you. A cigar is never just a cigar, and this particular lock of hair symbolizes the moral of the entire novel.