T.S. Elliot points out his thesis at the very beginning. The arguementative structure is arranged as follows:
1. presentation of the thesis (We dwell with satisfaction...can be isolated in order to be enjoyed)
2. focus on a precise category (poets) and explaination of the thesis using poet's point of view
3. focus on  the historical sense
4. explaination of the importance of the thesis: we can't belong to our traditions blindly.
5. Further point made : anyone who creates a new work of art changes the concept of that kind of work of art.

T.S. Elliot assures that poets are influenced by traditions and prejudices. The research of something new isolated to enjoy it is conditioned by the historical context, traditions, personal attitudes and personality. For these reasons impersonality seems to be impossible to reach. The poet could try to escape from traditions, but it's impossible to accomplished this attempt. We have to find a middle point: human beings (and so do poets) belong to tradition. We have to follow tradition but looking for something new, because the blindly chase does not improve human beings. This is the abstract concept that seems to feed the whole 20th century: this historical period is characterized by the incredible number of discoveries, innovations and upgrades in techincs, physics and science.
Returning to literature, the creation of something new is an uprgrade of that concept. A new work of art changes even the past experiences in  that kind of work of art. For instance, a poet could write a sonnet which maight be different from  the classical ones  (Petrarchian or Shakesperean) but he shouls still keep to its conventions. The new sonnet changes the entire concept of the sonnet, even if the model might remain the same  : same structure, same themes, but something changes in the way language expresses the private feelings that are typical of that era and as a result the concept changes too.

I agree with T.S. Elliot's thesis. I think that a new creation changes the concept of previous creations in that domain. For instance a new electronic song (I choose electronic music because it's my passion) is a potentially  new work of art because the minimum detail could make that song belong to a "new genre".

There are many examples: I quote Crookers, a two man-band that starting from House music creates music similar to House but different: they invented the Crook-House music as a matter of fact. If we follow traditions we will not be able to invent. The world needs innovations and it's our business to perform them.