The phrase "best poetry" refers to the most excellent or superior kind of poetry. It represents the highest quality or most exceptional poems that may evoke strong emotions, convey deep meaning, or exhibit impressive techniques.
The reading of good poetry also helps that part of the mind that uses language to limber up, relax a bit — it's akin to shaking your sillies out, in the terms of that children's song. (bookbrowse.com)