An Oak Tree
In 1974, he exhibited the seminal piece An Oak Tree. The work consists of a glass of water standing on a shelf attached to the gallery wall next to which is a text using a semiotic argument to explain why it is in fact an oak tree. Nevertheless, on one occasion when it was barred by Australian Customs officials from entering the country as vegetation, he was forced to explain it was really a glass of water. The work was bought by the National Gallery of Australia in 1977; however, the Tate gallery has an artist's copy.