One day Pedro Tercero takes his girlfriend to visit his granddad (Old Pedro García) and Gramps tells them a story. It goes a little something like this: every night, a mean old fox would sneak into a chicken coop and eat the baby chicks and steal the eggs. One day, the hens decided they weren't going to take it anymore. They banded together, and the next time the fox tried to sneak into their coop, they pecked him half to death and scared him away. The end.
Now, is this little tale just about foxes and hens? Um, no. Chances are good that the foxes and hens are meant to represent something else, and that the whole point of the story is to illustrate a moral lesson. One that's about weak, little people (like the tenant farmers at Tres Marías) who band together to defend themselves against the big, powerful people who take advantage of them (like Esteban Trueba).
For us, the most significant part about Old Pedro García's parable is the role it plays in characterizing Pedro Tercero as a young, upstart revolutionary. Pedro Tercero writes a song about his grandpa's parable – then he sings it right to the patrón's face. And then, just to make sure Esteban Trueba really gets it, he says: "If the hens can overcome the fox, what about human beings?" (5.50).
The fox and hens song keeps popping up throughout the novel, and whenever we read about it, we think of Pedro Tercero. It's kind of like his theme song. The ditty catches on with the peasants, who hum the tune even when they're skittish of Pedro Tercero's revolutionary ideas. It makes his dad proud, and it makes him rich and famous.