Not surprisingly in a writer and thinker whose greatest theme is humanity's all-encompassing wholeness, and who celebrates the individual's capacity to achieve union with the animating principle of Nature, images of unity and fragmentation play a major role in Emerson's writings. One aspect of this theme is an opposition of the organic and the mechanical, a concept congenial to a writer who revered nature as the supreme lawgiver and educator. Almost always, the organic is allied with that which is wholesome, good, and desirable; the mechanical is linked with that which is unhealthy, divisive, and destructive. For example, in "The Poet," Emerson advises the aspiring poet to seek themes in nature rather than in human history; his imagery contrasts the natural landscape with constructed and manufactured items like castles and swords: "O poet! a new nobility is conferred in groves and pastures, and not in castles or by the swordblade any longer."
Many times Emerson presents only the natural image, and the contrast is left to the reader's inference. Thus, in "The Over-Soul," the moral authority of the heart and feelings is implicitly opposed to mental or intellectual rules, which must have a divine spark of feeling in order to be worthwhile: "Speak to his heart and the man becomes suddenly virtuous. Within the same sentiment is the germ of intellectual growth, which obeys the same law." Occasionally, he departs from rigid application of the organic-versus-manufactured dichotomy to make comparisons in which a good or desirable element is paralleled with a constructed item. This often happens when the subject is related to science, a branch of learning he admires — conditionally — because it allows us a keener understanding of nature.
