Decorative devices, not essential to structure, but often necessary to emphasize or diminish the impact of structural elements, sometimes with iconographic rôles. Most cultures have evolved their own repertoires of architectural ornament, the sole exception being the C20 International Modern style. In Classical Antiquity, ornament (often repetitive, e.g. acanthus, anthemion and palmette, egg-and-dart, paterae, guilloche, Greek key, etc.) was an essential part of the sophisticated architectural language of the Orders, but ornament could be found in the civilizations of Mesopotamia (e.g. cone mosaics) and Ancient Egypt (e.g. stylized lotus, papyrus, etc) much earlier. Byzantine, Romanesque, and Gothic styles had their own ornament, e.g. transformations from the Classical repertory, chevron, beak-head, dog-tooth, nail-head, etc., and the Renaissance period rediscovered Classical ornament, which was often adapted and transformed in Mannerist, Baroque, and Rococo architecture. From the middle of C18, Neo-Classicism once more turned to archaeologically correct ornament with the works of architects such as Adam, Stuart, Wyatt, etc. When Gothic was revived, medieval ornament was again studied, copied, and then informed a new creativity. From C18 many styles (including oriental, Indian, and Islamic) were adopted in an enthusiasm for exotic eclecticism, and in C19 publications made a vast range of architectural ornament available in convenient form: among them may be cited the famous Grammar of Ornament by Owen Jones, a vast compendium, with colour-plates. Ruskin held that ornament was a principal element of architecture (a view that was anathema to Modernists), but he endowed it with moral and spiritual qualities that some might find odd. Semper noted that ornament used in the production of textiles might be used on walls constructed of different materials: he argued that in their transformations, materials used are of no great importance, and that ornament, far from being an afterthought, stuck on a building (as was often the case in C20), was more symbolic and essential to architecture than structure. Ornament, he insisted, was conditioned by tradition, and by millennia of evolution from its origins in patterns that appeared in Urkunst (original art, e.g. weaving). Semper was claimed by Modernists for their cause, but they clearly had not read or understood him. Fergusson (not much read in C21) claimed that ornament was the poetic element in architecture, while structure was altogether more prosaic. Certain architects, such as Sullivan, suggested ornament should be eschewed at least for a time, yet were themselves inventive and uninhibited users of architectural enrichment. Loos, in the Kärntner Bar, Vienna (1908), used rich materials and a stripped Neo-Classical language, while in the Scheu House, Hietzing (1912), the ingle-nook and library clearly drew on English Arts-and-Crafts domestic precedents. Yet Loos's fulminations against ornament are always quoted by Modernists, who also refer to his Steiner House, Vienna (1910), as an important work of Modern architecture, despite the fact that the symmetrical plan has Neo-Classical roots, and the interiors, with their exposed beams and joists, again are drawn from English exemplars. Perret used ornament very effectively (e.g. Rue Franklin apartments, Paris (1902) ), and it was an essential element in the work of, e.g. Hoffmann, Mackintosh, and Olbrich to name but three significant architects. More recently Outram has used ornament in an intelligent way, to the displeasure of some.