Poet v.s. Reader Influences on Literature

On page 957 of Tradition and the Individual Talent, T.S. Elliot explains that "he [the poet] must be quite aware of the obvious fact that art never improves, but that the material of art is never quite the same." 

"Material of art" could be seen as how the art is formed or written, which changes with new ideas and theories presented. 

How does this quote about a poet relate to the fact that T.S. Elliot believes that the reader's perception of a text is influenced by our past? (Does the reader and the poet approach a text in a similar way, or in a different way?) 

                                          Change in Draft = Change in Thought

                                                         

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