There is sorrow, but I hope one can see that it is sorrow for the people who died so young and so crazy, for nothing. I have respect for them, but also for their wishes, or for the power of their wishes. Because they tried to change the stupid things in the world.

The first colour charts were unsystematic. They were based directly on commercial colour samples. They were still related to Pop Art. In the canvases that followed, the colours were chosen arbitrarily and drawn by chance. Then, 180 tones were mixed according to a given system and drawn by chance to make four variations of 180 tones. But after that the number 180 seemed too arbitrary to me, so I developed a system based on a number of rigorously defined tones and proportions.

But my motivation was more a matter of wanting to create order - to keep track of things. All those boxes full of photographs and sketches weigh you down, because they have something unfinished, incomplete, about them. So it's better to present the usable material in an orderly fashion and throw the other stuff away. That's how the Atlas came to be, and I exhibited it a few times.

Contact with like-minded painters - a group means a great deal to me: nothing comes in isolation. We have worked out our ideas largely by talking them through. Shutting myself away in the country, for instance, would do nothing for me. One depends on one's surroundings. And so the exchange with other artists - and especially the collaboration with Lueg and Polke - matters a lot to me: it is part of the input that I need.

The desire to please is maligned, unfairly. There are many sides to it. First of all, pictures have to arouse interest before people will even look at them, and then they have to show something that holds that interst - and naturally they have to be presentable, just as a song has to be sung well, otherwise people run away. One mustn't underrate this quality, and I have always been delighted when my pieces have also appealed to the museum guards, the laymen.

And then the work bears a strong sense of leave-taking for me personally. It ends the work I began in the 1960s (paintings from black-and-white photographs), with a compressed summation that precludes any possible continuation. And so it is a leave-taking from thoughts and feelings of my own on a very basic level. Not that this is a deliberate act, of course; it is a quasi-automatic sequence of disintegration and reformation which I can perceive, as always, only in retrospect.

I am ridiculously old-fashioned.