Peter Märkli said: “The sketch is the germ of an idea, with no detail in it. The sketch has to be kept small, otherwise you’d have to flesh out certain details. It’s like a writer coming up with an idea for a novel. He might be clear that there will be three main characters, but he doesn’t yet know how the plot will unfold. Every time you have a motif, an idea, and you need a lot of drawings to work through it to the end. You might do ten and look and suddenly realise that you know enough at that moment, and the thing is finished. But then you might come back to that series much later. It’s perfectly possible. Twenty years after I did this series of facades made up of squares – different squares, not regular ones – I built a house using the same motif. The building and the situation and the landscape all needed this facade.”