It was not possible for us to produce the same optimism and the same kind of humour or irony. Actually, it was not irony. Lichtenstein is not ironic but he does have a special kind of humour. That's how I could describe it: humour and optimism. For Polke and me, everything was more fragmented. But how it was broken up is hard to describe.

To me, grey is the welcome and only possible equivalent for indifference, noncommitment, absence of opinion, absence of shape. But grey, like formlessness and the rest, can be real only as an idea, and so all I can do is create a colour nuance that means grey but is not it. The painting is then a mixture of grey as a fiction and grey as a visible, designated area of colour.

Well, the beginning is actually quite easy, because I can still be quite free about the way I handle things - colours, shapes. And so a picture emerges that may look quite good for a while, so airy and colourful and new. But that will only last for a day at most, at which point it starts to look cheap and fake. And then the real work begins - changing, eradicating, starting again, and so on, until it's done.

I believe that art has a kind of rightness, as in music, when we hear whether or not a note is false

Maybe we didn't even have a chance. The message of American Pop Art was so powerful and so optimistic. But it was also very limited, and that led us to believe that we could somehow distance ourselves from it and communicate a different intention.

Without form, communication stops... without form, you have everybody burbling on to themselves, whenever and however, things that no one else can understand and - rightly - no one else is interested in.

The urge to break with a tradition is only appropriate when you're dealing with an outdated, troublesome tradition: I never really thought about that because I take the old-fashioned approach of equating tradition with value (which may be a failing). But whatever the case, positive tradition can also provoke opposition if it's too powerful, too overwhelming, too demanding. That would basically be about the human side of wanting to hold your own.