The phrase "Let's put, by caution, another candle to the devil" from Arturo Pérez-Reverte's book "All Alatriste" suggests a sense of pragmatic caution when dealing with challenges or adversities. It reflects the idea that, in uncertain or dangerous situations, it may be wise to take precautionary measures, even if they seem superstitious or unnecessary. The imagery of lighting a candle for the devil evokes themes of acknowledging risks while navigating the complexities of life and morality.

This sentiment is particularly resonant in the context of the novel, which encapsulates the struggles of its protagonist, Captain Alatriste. The story set in 17th-century Spain explores themes of honor, duty, and survival, where characters often find themselves at moral crossroads. By highlighting the need for caution, Pérez-Reverte invites readers to contemplate the lengths one may go to in order to protect oneself, even invoking a metaphor as dark as the devil himself.