What priceless book does montag have?

Montag has a copy of the Bible in his possession. It's a priceless book because it represents knowledge, history, and a different way of thinking than the society he lives in.

While it's not explicitly stated that it's a Bible, it's heavily implied. Here's why:

* The Book of Ecclesiastes: In the novel, Montag describes the book as having "a lot of words about birds and fishes and trees." This is a reference to the Book of Ecclesiastes, a book in the Bible, known for its poetic language and reflections on nature.

* The Significance of the Book: The book Montag holds is a symbol of hope and resistance against the oppressive regime that burns books. The Bible holds similar significance in many cultures as a source of moral guidance, spiritual inspiration, and a challenge to the status quo.

Although Montag doesn't explicitly state the name of the book, the context and descriptions strongly suggest that it's the Bible.