Persevering is being used as a verb. verbs are action words, to persevere is an action. noun is a person place or thing, adjectives describe nouns or other adjectives, adverbs describe a verb.
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.
Making Inferences is the reading strategy that involves combining prior knowledge with new information or merging elements from multiple texts, to gain new insights.