Symbolism, Imagery, Allegory
Did you chuckle as much as we did whenever Gramps Hiddle said, "'this ain't our marriage bed, but it will do'"? Did you cry as much as we did when Gramps Hiddle slept in the hospital bed with Gram when she was so sick, and said, "'this ain't our marriage bed, but it will do'"? Or when, after Gram is gone, he can't finish the sentence and Sal has to finish it for him? The marriage bed packs an emotional wallop, and it's an important symbol in the story to boot.
The actual marriage bed is at Gram and Gramps' house in Bybanks. They've had it since the first day they were married. Before that, it belonged to Gramps' parents. He and his siblings were born in that bed. The marriage bed is full of history.
Okay, now here comes the fascinating part. The marriage bed is also a symbol of their marriage and how much they love each other. It represents all of the years they have been married and devoted to one another. No matter where they are, they bring their marriage bed with them in their minds, because Gramps always recites his saying. No matter how mad they are at each other, their marriage bed connects them and reminds them of their love for one another.
Plus, the bed helps connect Sal to her family history. Our girl's quite curious about her roots, and with all those generations sleeping in that bed, it's a symbol of all of this history.