Philip Pullman's first two Sally Lockhart books, The Ruby in the Smoke and The Shadow in the North, were engaging stories, but they did not have substance. They were the kind of books that successfully held my attention, but did not have a lasting impact.
The third book, The Tiger in the Well, had so much more substance. It brought to life some issues of the day, such as poverty and anti-immigrant sentiment. It was good to see history from that perspective, the texture of life for the underclass, rather than just hearing about kings and wars and treaties. Reading about the issues was also important because those issues are still relevant today.
Another big improvement was that in the final confrontation, the good guys (Sally in one scene and Dan in another) showed compassion for their enemies. I don't like books where the bad guys are just evil. I like books that show that we are all just human, and that show why the bad guys do what they do. The scene in which Dan quelled mob violence by understanding the humanity of those who would attack him was to me one of the most important parts of the book.
After reading the fourth book in the series, The Tin Princess, at first I thought that it was another engaging story, and that it lacked both substance and a satisfying ending. But then as I thought about it, I began to see the substance in the ending. Often in stories, including all four Sally Lockhart books, the good guys win when the bad guys meet their demise. Sometimes that demise comes as a result of violent action on the part of the good guys. The problem with this is that when a person uses violence to achieve their goals, it's hard to believe that they are truly good guys. In order to get around this problem, often what happens is there is a confrontation that comes about as a result of the evil of the bad guys, but somehow in the confrontation, the bad guy ends up dying, though not at the hands of the good guy. For example, in attacking the good guy, the bad guy ends up falling off a cliff. This device is over-used, and I think it's kind of dumb. It says violence is the only resolution, but we don't want to sully the good guy's hands. In such cases, the author seems unable to imagine any resolution other than violence. That's why Dan's quelling the mob in The Tiger in the Well was so important, because it was a true nonviolent resolution.
In The Tin Princess, there are some battles which the good guys win through either violence or through the over-used device of accidental demise in confrontation. They win some battles, but they lose the war. The reason they lose the war is because the violence of the bad guys is mightier than the violence of the good guys. That happens sometimes in life. But the point that the book makes is that although that happens sometimes, it's not the end of the world. The book closes with the hope that both the big picture political situation and the lives of the individuals will move forward to a brighter situation. As Sally says, "Life's not static, you see, Becky. Life's dynamic. Everything changes. That's the beauty of it" (p. 286).
We see a metaphor for this in Sally's reaction to learning that the sweater she put so much time into knitting had been unraveled. Jim unraveled it to use it for their survival. "When she'd heard what Jim had done with the jersey she'd knitted, she laughed with pure happiness, as if there were no final dark, as if the whole universe were a joyful play of light" (p. 286). Sometimes violence wins, and destroys the things we were trying to create, but even when the things we were trying to create are unraveled, we can create new things out of what remains. That is the final message of The Tin Princess.