During Montag's life he believed that as a fireman, that all books should be burned. But one day his view of burning books changed. When him and the other firemen went to the old ladies house to burn her books, she decided to die along with the books. Montag believed that there might be something important about books, so he decided to steal books and hide them in his house and eventually figure out the secret about books.
A way Montag was ambitious was by having a burning desire to be a firemen. In the first part of the book he claimed that he loved to be a firemen and he loved to burn books even though he didn't know the real reason was to burning them. His strong desire for burning books made him ambitious.