"I was aware of the nature, it suddenly dawned on me, about this business of abstraction. I always think abstractly but the problem was that it didn't come into the work. And it is this, that when the bomb blows the building apart it abstracts it, the pieces fall back together again and you get a memory image of what was there but vastly altered and psychologically made infinitely more intense than the original thing. So that was a process of abstracting. Well, I started thinking of bomb ruins in terms of 'here was a building and here are the abstract elements of it.' I worked from there."