"I think you were speaking of dogs killing rats," Pitt remarked mildly, handing his cousin the decanter to "buzz."
"Killing rats, was I? Well, Pitt, are you a sporting man? Do you want to see a dawg as can kill a rat? If you do, come down with me to Tom Corduroy's, in Castle Street Mews, and I'll show you such a bull-terrier as–Pooh! gammon," cried James, bursting out laughing at his own absurdity,–"you don't care about a dog or rat; it's all nonsense. I'm blest if I think you know the difference between a dog and a duck."
"No; by the way," Pitt continued with increased blandness, "it was about blood you were talking, and the personal advantages which people derive from patrician birth. Here's the fresh bottle."
"Blood's the word," said James, gulping the ruby fluid down. "Nothing like blood, sir, in hosses, dawgs and men. Why, only last term, just before I was rusticated, that is, I mean just before I had the measles, ha, ha–there was me and Ringwood of Christ-church, Bob Ringwood, Lord Cinqbar's son, having our beer at the 'Bell' at Blenheim, when the Banbury bargeman offered to fight either of us for a bowl of punch. . . . Bob had his coat off at once–he stood up to the Banbury man for three minutes, and polished him off in four rounds easy. Gad, how he did drop, sir, and what was it? Blood, sir, all blood."

This lively exchange between James and Pitt Crawley underscores the theme of class and breeding in Vanity Fair. James, with his brash, sporting bravado, equates the value of "blood" with prowess, whether in animals or aristocrats. His stories, tinged with humor and exaggeration, highlight the perceived superiority and entitlement among those of noble lineage. Pitt's polite prodding and the mention of "patrician birth" draw James into the very topic of hereditary privilege, poking fun at the young man's grandiose tales of brawny exploits. The metaphor of "blood" becomes a lens through which the characters view social hierarchy, revealing how deeply entrenched these ideas are in their society. James's mention of a noble friend's fighting skills further amplifies the absurdity of equating noble birth with physical strength, making it a pointed commentary on the era's fixation with class distinctions.