For many people it is an 'article of faith' [=something that is believed without being questioned or doubted] that the economy will begin to improve soon.
In “I gave a book to the boy” the word “a” is an 'indefinite article' and the word “the” is a definite article.
A lot of people pretend to be cowboys, but he's 'the genuine article'. [=he's a real cowboy]
(..) Come here a minute. What? This canvas report is ready. If Andy okays it, send copies to headquarters... I got to get that article Xeroxed. That has to be... - Don't forget the new photos. - I didn't forget. Look... We have to emphasize the Mandatory Welfare Program. (..)1976 Taxi Driver