Dan "O'Hara argues that, strictly speaking, the term skeuomorphism refers only to those vestigial elements in nature or artefact that survive from an original form, even though they are no longer required. At its broadest, this definition extends to the levers and dials in a modern aircraft cockpit, for example, which no longer connect to systems directly, but instead are merely inputs and outputs of a computer that actually controls things. Such controls are skeumorphs because they are holdovers from the days before computerised aircraft, and have been left in their original form for the benefit of pilots, who are used to them working in a particular way.
So can a digital depiction of something properly be called a skeuomorph? It is more accurate to refer to it as a visual metaphor that calls to mind a physical skeuomorph without really being one. The iPhone's notification panel, with its imitation linen effect, was not descended from an object that was once made of linen. The switch that, say, allows you to switch an iPhone into Airplane Mode is not an on–screen replacement for what used to be a physical switch. In the early days of graphical user interfaces, designers employed familiar devices, such as folders, trash cans and other objects commonplace in the office. The result was that operating systems ended up being littered with depictions of things that had never existed inside a digital device; the on–screen 'trash' icon is not the vestigial remnant of an actual trash can that was once part of the computer, which is why it is really a metaphor, not a skeumorph. (That said, as computer graphics became more detailed, the original blocky icons gave way to more detailed depictions of trash cans, folders and so forth, which are arguably skeuomorphs of visual metaphors.)"
(Glenn Fleishman, 25 June 2013, The Economist)
"We have long been familiar with the power of the Chinese to balance colours, but we were not so well acquainted with their power of treating purely ornamental or conventional forms ; and in the chapter in the Grammar of Ornament on Chinese Ornament I was led, from my then knowledge, to express the opinion that the Chinese had not the power of dealing with conventional ornamental form : but it now appears that there has been a period in which a School of Art existed in China of a very important kind. We are led to think that this art must in some way have had a foreign origin; it so nearly resembles in all its principles the art of the Mohammedan races, that we may presume it was derived from them. It would be no difficult task to take a work of ornament of this class, and, by simply varying the colouring and correcting the drawing, convert it into an Indian or Persian composition. There is of course, in all these works, something essentially Chinese in the mode of rendering the idea, but the original idea is evidently Mohammedan. The Moors of the present day decorate their pottery under the same instinct, and follow the same laws as the Chinese obeyed in their beautiful enamelled vases. The Moorish artist takes a rudely–fashioned pot or other object, and by a marvellous instinct divides the surface of the object, 'by spots of colour, into triangles of proportionate area, according to the form and size of the object; these triangles are then crossed by others."
(Owen Jones, 1867)
Owen Jones (1867). "Examples of Chinese Ornament Selected from Objects in the South Kensington Museum and Other Collections: By Owen Jones. One Hundred Plates", S. & T. Gilbert, 4 Copthall Buildings, E.C. Back of the Bank of England.