One of his most famous works is “One and Three Chairs”, a visual expression of Plato’s concept of The Forms. The piece features a physical chair, a photograph of that chair, and the text of a dictionary definition of the word “chair”. The photograph is a representation of the actual chair situated on the floor, in the foreground of the work of art. The definition, posted on the same wall as the photograph, delineates in words the concept of what a chair is, in its various incarnations. In this and other, similar works, Five Words in Blue Neon and Glass One and Three, Kosuth forwards tautological statements, where the works literally are what they say they are.
A sign is anything that can be used to tell a lie.