sorrow that can't talk

I'm reading Jogn Steinbeck's The Grapes of Wrath, out of which I read the following passage, in which the Oklahomy Joad family attempts to unsuccessfully sell all of their belongings to make money for their great trip to California.

Now, what'll you give for the team and wagon? Those fine bays, matched they are, matched in color, matched the way they walk, stride to stride. In the stiff pull-- straining hams and buttocks, split second timed together. And in the morning, the light on them, bay light. They look over the fence sniffing for us, and the stiff ears swivel to hear us, and the black forelocks! I've got a girl. She likes to braid the manes and forelocks, puts little red bows on them. Likes to do it. Not any more. I could tell you a funny story about that girl and that off bay. Would make you laugh. Off horse is eight, near is ten, but might of been twin colts the way they work together. See? The teeth. Sound all over. Deep lungs. Feet fair and clean. How much? Ten dollars? For both? And the wagon-- Oh, Jesus Christ! I'd shoot 'em for dog feed first. Oh, take 'em! Take 'em quick, mister. You're buying a little girl plaiting the forelocks, taking off her hair ribbon to make bows, standing back , head cocked, rubbing the soft noses with her cheek. You're buying years of work, toil in the sun; you're buying a sorrow that can't talk.