While metaphor constitutes one of the most important phenomena studied by cognitive semantics and cognitive poetics, one specific type of metaphor, the so-called image metaphor, receives little attention in cognitive theory and research. Image metaphors are quite frequent in poetry and prose, especially in descriptions of the natural world. They are markedly different from conventional conceptual metaphors and entrenched metaphorical expressions found in everyday language, as they do not involve a more tangible source domain and a more abstract target domain. In an image metaphor, both the source and the target are specific physical entities. Unlike conceptual metaphors, which help people to conceptualize, reason and talk about abstract concepts and ideas in terms of more tangible domains, image metaphors serve entirely different purposes. They emphasize certain similarities between various entities or they create such similarities. The article presents a small part of my study of image metaphors in descriptions of nature in Thoreau’s writings. It focuses on image metaphors in two of his later, less known and discussed texts: the essay “Autumnal Tints” and his last manuscript called “The Dispersion of Seeds.” Thoreau uses image metaphors in order to point out that the natural world is full of likenesses and universal patterns or in order to defamiliarize ordinary phenomena which he describes.