Emerson now tackles the difficult question of subjective truth and the impossibility of verifying the truth of external reality. It is not possible to prove absolutely that what our senses perceive is real. The average person — Emerson uses the carpenter as one example of such a person — doesn't want to know that what he thinks is real might be an illusion. However, whether or not nature exists as something distinct from ourselves remains definitively unanswerable.
After declaring that it makes no difference whether external reality exists or not, Emerson begins his discussion of idealism. His first point concerns visual changes and distortions caused by mechanical apparatuses, or by our physically changing the way we interact with our environment. These changes and distortions emphasize the separation between ourselves and nature, a separation that produces wonder and provides us with a sense of our own stability. We come to believe that although the world around us changes, in part due to our causing it to, we stay constant. As Emerson notes, "We are not built like a ship to be tossed, but like a house to stand."
Emerson exalts the poet as producing the most ideal — and, therefore, the most real — forms inspired by nature. When creating a poem, the poet actually manipulates nature. Figuratively speaking, objects "shrink" and "expand" according to the poet's needs: Some objects become more important symbolically than the poet's audience might have originally thought, or an object as large and magnificent as a mountain might be used by the poet to symbolize an idea that we consider not very important. Emerson uses Shakespeare's figurative language as an example, quoting from some of his sonnets and from his play The Tempest. He cites Shakespeare's metaphor of time as a chest out of which a lover cannot escape to get to the beloved. Whereas we usually view time as non-constrictive, here Shakespeare uses it as an object that restricts.
Emerson now discusses the differences between the poet, the philosopher, and the scientist. The poet is concerned with beauty, the philosopher with truth. Both are engaged in spiritualizing the physical world using mental processes, but the philosopher is more likely to be trapped in his thoughts, discarding nature's objects from which his ideas were originally gained. In contrast, scientists, and especially mathematicians, rely on abstract reasoning rather than physical observation. Philosophers dismiss nature's objects "like an outcast corpse" once they are through using them, and scientists fail even to begin with an object as the starting point for their work. The theme of accessibility is present in this section when Emerson notes that although great ideas are accessible to few men and women, all persons are capable of training themselves in the art of critical thinking.
The last point that Emerson considers in this section about idealism is the relationship of ethics and religion to nature. He finds that these two disciplines relegate nature to an inferior position in a scheme of values that regards spiritual truth as the only valid truth. Religion urges the individual to deplore the physical world and distrust the body, and both ethics and religion "put nature under foot." Recommending that the individual focus on nature's totality, Emerson cautions against excessively detailed inquiries into ethics and religion.
Overall, Emerson asserts the power and importance of ideas. Again using a circle to symbolize the interrelated universe of people and nature, he emphasizes that the universal ideas grounding us in this world are products of a Supreme Being. A person who contemplates universal ideas gains new heights of understanding and, according to transcendental philosophy, transcends time and space to attain a metaphysical consciousness and immortality.