Why did tolkien call chapter 16 a thief in the night rather than burglar night?

You're likely thinking of the chapter title "A Thief in the Night" from J.R.R. Tolkien's *The Fellowship of the Ring*. The chapter title isn't actually "Burglar Night," and Tolkien didn't choose the title "Thief in the Night" for any specific reason that we know of.

However, there are some reasons why "Thief in the Night" might be a more fitting title than "Burglar Night":

* Connotations: "Thief" has a broader and more sinister connotation than "burglar." It evokes a sense of stealth, secrecy, and perhaps even danger. This aligns well with the events of the chapter, where the Fellowship is trying to escape the Black Riders and navigate through the perilous Mines of Moria.

* Biblical reference: "Thief in the Night" is a phrase used in the Bible (e.g., 1 Thessalonians 5:2-4), which suggests a sudden and unexpected event. This could be seen as a metaphorical reference to the Fellowship's unexpected encounter with the Balrog within the Mines of Moria.

* Literary style: Tolkien was known for his rich and evocative language, and "Thief in the Night" is a more poetic and atmospheric title than "Burglar Night." It creates a sense of suspense and mystery, drawing the reader further into the story.

Ultimately, Tolkien's choice of title was likely driven by a combination of these factors, and the specific reasoning remains unknown.