@Phil's answer is a much better explanation of the phonetics than I could give, but I have a small correction about "Beauty and the Beast."
It's titled that way because "Beauty" is the proper name of the character. "The Beast" takes an article because "Beast" is his title. It's the same structure as the title of the movie "Snow White and the Seven Dwarves," and the book and movie "Anna and the King of Siam."