Is a poem about nature beautiful because of its form, or is it beautiful because

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Is a poem about nature beautiful because of its form, or is it beautiful because it reminds us of the beauty inherent in nature? Philosophers tend to equate aesthetic beauty with the form of a work of art and our 'interests' get in the way of appreciating the form. However if this is the case why is there not more beautiful poems about rubbish dumps and oil spills.