Curtains don't come up a ton in this book, but they're such a classic symbol that we figured we'd give them a shout-out in this section. Any time curtains come up in books or movies, it's a good idea to make note of what they are hiding or showing. Insofar as curtains have the ability to show things and to let in light (or, conversely, to hide things and shut light out), they represent a character's relationship to truth and their willingness to accept it—because nothing represents truth better than light and choosing to see the world.
Let's look at a passage involving curtains, Tom, and Gemma to get a better grip on this symbol:
"We have to go through the East End. Whitechapel? Oh, for heaven's sake, the slums, Gemma," he says, loosening the curtains on the sides of his windows to block out the poverty and filth.
"I've seen slums in India," I say, leaving my curtains in place. (3.52-53)
The coach driver calls back to Tom to warn him that they're going to pass through the slums, suggesting that this is standard practice when chauffeuring rich folks through the city. It's easier to enjoy your wealth, after all, if you never have to confront abject poverty. And Tom is happy for the heads up, and promptly sets about closing his curtains—closing his eyes to the truth of the city—but Gemma is put off by this practice. And not only does she leave her curtains open, but she looks out the window and watches the lives of the poor as they pass through.
Tom consistently shows disinterest in the truth, and his eager use of the curtains here reminds us of that. Whether saying his mother died of illness (instead of being murdered) or denying his father's addiction, Tom likes to stick to socially accepted stories and prefers not to dig deep. Gemma, on the other hand, is curious about the world and her place in it, and struggles every time she is pressured to be dishonest about who she is. And who consistently pressures her to hide her truth? Tom. That's who.