Actually literary texts uses common words available in the language but in a creative way. Poetic diction may simply means that the words used in poetry tend to have greater beauty and inherent aesthetic potential than others. At some times, it was felt that the greatest beauty lies in the vocabulary of "common speech", a view commonly associated with Wordsworth.
Wordsworth started to use common language in his poetry to address the common man. Basher ibnu Bord did the same. He is one of the innovators of Arabic poetry. He said:

Now we no longer think of words as being inherently beautiful or ugly or of beauty as residing in the language itself. We see it as a matter of tradition or new creation familiarity or non-familiarity. It is after all a matter of convention, and a sincere desire to stick to the convention or to contradict it