Throughout the series, Stroud explores the seductive and ultimately corrupting nature of power. In "Ptolemy's Gate," this theme reaches its climax. We see how the pursuit of power has twisted even the most well-intentioned individuals, like Nathaniel, who becomes increasingly ruthless and isolated. On the other hand, the common people, both human and magical beings, bear the brunt of the powerful's ambition, suffering under oppressive rule and endless conflicts.

Even in a world where magic offers a seemingly easy path to dominance, Stroud emphasizes the significance of free will and individual choice. Bartimaeus, bound to serve, constantly grapples with his own desires and loyalty. Nathaniel must confront the repercussions of his choices and decide what kind of leader he will become. Ultimately, the characters face crucial decisions that will determine not only their own fates but also the future of their world.

Faced with overwhelming odds, humans and magical beings must overcome their prejudices and long-held hatred to stand a chance against a common enemy. The evolving relationship between Nathaniel and Bartimaeus, built on begrudging respect and understanding, exemplifies this. The fate of their world hinges on their ability to bridge the divide and fight together.