I began in 1976, with small abstract paintings that allowed me to do what I had never let myself do: put something down at random. And then, of course, I realized that it never can be random. It was all a way of opening a door for me. If I don't know what's coming - that is, if I have no hard-and-fast image, as I have with a photographic original - then arbitrary choice and chance play an important part.

I believe that you always have to believe. It's the only way; after all we both believe that we will do this exhibition. But I can't believe in God, as such, he's either too big or too small for me, and always incomprehensible, unbelievable.

I began in 1976, with small abstract paintings that allowed me to do what I had never let myself do: put something down at random. And then, of course, I realized that it never can be random. It was all a way of opening a door for me. If I don't know what's coming - that is, if I have no hard-and-fast image, as I have with a photographic original - then arbitrary choice and chance play an important part.

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.

Perhaps the Doors, Curtains, Surface Pictures, Panes of Glass, etc. are metaphors of despair, prompted by the dilemma that our sense of sight causes us to apprehend things, but at the same time restricts and partly precludes our apprehension of reality.

I never worked at painting as if it were a job; it was always out of interest or for fun, a desire to try something.

Based on mixtures of the three primary colours, along with black and white, I come up with a certain number of possible colours and, by multiplying these by two or four, I obtain a definite number of colour fields that I multiply yet again by two, etc. But the complete realization of this project demands a great deal of time and work.