It's called Oak Tree. It was first exhibited at the Tate Modern in the early 70's. Part of the piece is the explanation which is printed on paper next to it. Here:
The text reads like this:
Q. To begin with, could you describe this work?
A. Yes, of course. What I've done is change a glass of water into a full-grown oak tree without altering the accidents of the glass of water.
Q. The accidents?
A. Yes. The colour, feel, weight, size ...
Q. Do you mean that the glass of water is a symbol of an oak tree?
A. No. It's not a symbol. I've changed the physical substance of the glass of water into that of an oak tree.
Q. It looks like a glass of water.
A. Of course it does. I didn't change its appearance. But it's not a glass of water, it's an oak tree.
Q. Can you prove what you've claimed to have done?
A. Well, yes and no. I claim to have maintained the physical form of the glass of water and, as you can see, I have. However, as one normally looks for evidence of physical change in terms of altered form, no such proof exists.
Q. Haven't you simply called this glass of water an oak tree?
A. Absolutely not. It is not a glass of water anymore. I have changed its actual substance. It would no longer be accurate to call it a glass of water. One could call it anything one wished but that would not alter the fact that it is an oak tree.
Q. Isn't this just a case of the emperor's new clothes?
A. No. With the emperor's new clothes people claimed to see something that wasn't there because they felt they should. I would be very surprised if anyone told me they saw an oak tree.
Q. Was it difficult to effect the change?
A. No effort at all. But it took me years of work before I realised I could do it.
Q. When precisely did the glass of water become an oak tree?
A. When I put the water in the glass.
Q. Does this happen every time you fill a glass with water?
A. No, of course not. Only when I intend to change it into an oak tree.
Q. Then intention causes the change?
A. I would say it precipitates the change.
Q. You don't know how you do it?
A. It contradicts what I feel I know about cause and effect.
Q. It seems to me that you are claiming to have worked a miracle. Isn't that the case?
A. I'm flattered that you think so.
Q. But aren't you the only person who can do something like this?
A. How could I know?
Q. Could you teach others to do it?
A. No, it's not something one can teach.
Q. Do you consider that changing the glass of water into an oak tree constitutes an art work?
Q. What precisely is the art work? The glass of water?
A. There is no glass of water anymore.
Q. The process of change?
A. There is no process involved in the change.
Q. The oak tree?
A. Yes. The oak tree.
Q. But the oak tree only exists in the mind.
A. No. The actual oak tree is physically present but in the form of the glass of water. As the glass of water was a particular glass of water, the oak tree is also a particular oak tree. To conceive the category 'oak tree' or to picture a particular oak tree is not to understand and experience what appears to be a glass of water as an oak tree. Just as it is imperceivable it also inconceivable.
Q. Did the particular oak tree exist somewhere else before it took the form of a glass of water?
A. No. This particular oak tree did not exist previously. I should also point out that it does not and will not ever have any other form than that of a glass of water.
Q. How long will it continue to be an oak tree?
A. Until I change it.What f#cking tedious nonsense. I didn't get much further than the first 10 lines or so. It's b#llcks. Everyone knows it's b#llocks. In what way does it do anything but a discredit to the word "art" when you go in a gallery and see a pair of dangly b#llocks hanging there? Infuriating.
The only positive is that it made me feel quite affectionate towards my old "modern art bit" which I've so far not used as part of my stand up set. It's here. Maybe I should pull it out of the bowels of my mind and give it a good airing when I do my next performance. Not long now. Smaller venue this time though. No gong either!
I feel a little bit like a philistine now, so to make amends here's some good art:
Most of the stuff there was good. Well done everybody.
*Not his real name, just an amusing name which is explained by this YouTube video.
** That term now seems pleasantly anachronistic.