The Blackthorn Key

From Christopher’s first foray into mixing gunpowder to his decoding of Master Benedict’s ledger page, he needs to decipher his master’s ciphers. These ciphers come into play when he finds the spare key at Hugh’s house, marked by the symbol for the planet Mars. Similarly, they show up in the puzzle cube, which teaches Christopher to look for the missing planet/element Mercury. This type of training allows Christopher to follow his master’s note and track down the recipe for the Archangel’s Fire. As the story unfolds, it becomes clear that Master Benedict uses these symbols as a form of protecting both his knowledge and his apprentice; this succeeds. However, the time it takes for Christopher to solve these ciphers places him in extreme peril.

Sands’ presentation of ciphers is thus not entirely positive. Symbols are a form of deception, replacing something with another to disguise it. While deception does assist Christopher on his quest at points, such as when he dresses as a street urchin to avoid capture as a murderer, it also imperils him. For example, when Christopher pretends to be somebody else to approach Isaac, Isaac initially refuses to help him.