Repetition and language are themes found again and again throughout Earth, a gathering of objects that explores the elemental and natural dimensions of the work of conceptual artist Theresa Hak Kyung Cha (1951–1982). Drawn from the artist's archive in BAMPFA's Conceptual Art Study Center, the exhibition includes artist's books, works on paper and fabric, sculpture, video, and a color-slide piece by Cha that has never before been exhibited in the United States. Cha's French-language artist's book L'Image Concrète, feuille, L'Objet Abstrait (1976) is a work of concrete poetry in which Cha evokes the concept of falling leaves by repeating and altering the French word feuille. Feuille translates to leaf, sheet, to turn over the leaves of, to thumb through. Throughout the text Cha manipulates the word by isolating letters, creating patterns of characters, transforming the term from feminine to masculine, from noun to verb-multiplying the possible meanings contained in seemingly simple language. Leaves reappear in Population Ring, Clifton Street (1977), in which photocopied pages alternate between French text and images of fallen leaves on a brick sidewalk. Among the leaves one can glimpse words, which are isolated and repeated on the following page. An untitled 1977 slide piece (here digitized and displayed on a monitor) documents an artist's book in which Cha uses envelopes evocative of medicine packets, each one labeled with press-type letters spelling out a day of the week, in French on one side and Korean on the other. Inside each envelope is an origami bindle containing natural materials such as salt, ash, earth, flour, and leaves or press-type words like water, earth, and moon, again encouraging the viewer to consider the relationship between the abstraction of language and the phenomena of the natural world. For Repetitive Pattern (1975), Cha cut sixty different-sized strips of white cloth, stenciled them with words and symbols in black ink, and sewed them to a piece of white fabric. The stenciled words and symbols are repeated in four columns; two of these reiterate the work's title. Here as in so many of Cha's works, language is transformed through manipulation, repetition, and reduction to its component parts.