Artworks that engage with conceptual issues surrounding language, such as translation, the relationship between words and images, and semiotics. Such works typically include written texts, but some engage language more obliquely; for instance, Leon Ferrari often abstracted the formal elements of writing, and artists associated with Dada addressed the arbitrariness of linguistic meaning through the use of nonsense speech. The Rosetta Stone (196 B.C.), inscribed in three languages, is one of the earliest artifacts that demonstrated the need for translation in order to communicate history. The use of language as a primary material emerged as a central feature of Conceptual Art, as embodied in Joseph Kosuth's works involving images and corresponding dictionary definitions, or Lawrence Weiner's treatment of language as sculptural matter. The text-based works of Jenny Holzer and Barbara Kruger present language as a form of power and authority, using it both to startle and to amuse, while Ed Ruscha, in his paintings, explores the clichéd language of pop culture.