I believe that there are three prepositional phrases but if you would like to do it yourself instead of taking my word for it. a prepositional phrase is a modifying phrase consisting of a preposition and its object.
And a preposition is a word governing, and usually preceding, a noun or pronoun and expressing a relation to another word or element in the clause, as in “the man on the platform,” “she arrived after dinner,” “what did you do it for ?”<span />
Robert frost is saying that when the reader first reads the poem in he beginning it should be playful and make the reader interested and grasp the topic, but by the end the poem should bring wisdom or a lesson. By the end of the poem the reader should have taken something out of the poem and learned something from it.
A.experience increased feelings of anxiety
