In "Mending Wall," the speaker's attitude toward the wall is one of skepticism and questioning. He questions why the wall is necessary and whether it truly serves a purpose. He sees the wall as a barrier that separates him from his neighbor, and he wonders why they need to be separated in this way. He notes that nature itself does not have walls, and he suggests that the wall is more about tradition and habit than anything else. Overall, the speaker seems to be critical of the wall and what it represents.
This attitude is different from Frost's attitude about structure in poetry. Frost believed that structure was an essential component of poetry, and he often used traditional forms such as sonnets and villanelles in his own work. However, he also believed that structure should not be overly restrictive and that it should serve the needs of the poem rather than the other way around. In other words, structure should be a tool for the poet to use in order to create meaning and beauty, rather than a set of rules that must be followed at all costs.
Overall, while the speaker in "Mending Wall" is critical of the wall and what it represents, Frost's attitude toward structure in poetry is more nuanced. He sees structure as an essential component of poetry, but he also believes that it should be flexible and adaptable to the needs of the individual poem.