In this fourth section, Emerson discusses the relationship between nature and language: Words represent objects in nature; these individual objects signify spiritual realities; and nature symbolizes spirituality.
To explain how words represent natural objects, Emerson uses etymology — the origin and development of words — to illustrate that abstract terms are derived from words for physical things. According to this view, which has been discredited by modern linguists, language is a series of metaphors, symbols representing other things. For example, at one time spirit evoked the word wind; we use the word heart to express emotion; and head is often synonymous with reason. These meanings are incorporated into our language to such a great extent that we forget the ways that words and their meanings originate.
Nature, as the interpreter between people, supplies the language that people use to communicate with. A river, for example, expresses the passage of time, and the seasons of the year correspond to the stages of human growth. Emerson naively assumes that these correspondences are universal and understood by all human beings. For example, he says that all people recognize that light and dark figuratively express knowledge and ignorance, respectively. This theme of universal understanding is emphasized further when he claims that each individual shares a universal soul linking that person to all others, as well as to the whole of nature.
This point about language acting as an interpreter between people recalls the idea of creation in the essay's introduction, where Emerson suggested that the act of creation and the vitality associated with that act have been lost. Here, he provides a reason for this loss of creativity: We are too easily corrupted by desires, including the desire for riches, for pleasure, and for power. Because these desires overly complicate our lives, we become distanced from nature's restorative powers, and the vital act of creation is lost: "New imagery ceases to be created," and words become tools that we use to deceive each other.
In the third section of this chapter, Emerson discusses how nature assumes spiritual dimensions through our use of language. The reasoning behind this claim is complex. Our human laws appear to mimic nature's laws, yet over time we have blurred the distinction between our laws and nature's. However, we cannot consider nature as something totally outside ourselves because "the whole of nature," Emerson states, "is a metaphor of the human mind," established so that we might have control over our lives. For example, he equates laws of physics as equivalent to rules of moral conduct.
Another important theme in this essay concerns the question of accessibility. Discussing the relationship between the intellect and nature, Emerson observes that the language used to make sense of the world can be known by all of us, not just poets: "This relationship between the mind and matter is not fancied by some poets, but stands in the will of God, and so is free to be known by all men." For those of us who are unsure of just how nature will become accessible, he assures us that "by degrees" we can come to understand nature and our relationship to it, and the world eventually will become "an open book" from which all can read.