One trap door closes and another one opens onto a world of dust and absolute darkness. In this wooden cave below the snow the weather creaks in and notes come from the piano. The music sends a shiver that's strangely like flying and the cold is severe but there's no option, now, but to keep on going. I wouldn't have it any other way, ascending the first frosted rampart indented with footholds for giants until a narrow way reaches the tops of the yews – so close you can hear them breathing, smell their berry breath as the first rampart completes the outer ring of a series of ever decreasing concentric circles. Here, you can, like me, walk for an eternity through roots, the bones of the trees exposed by erosion. What I walk on is a thin layer of grey clay spread on chalk where, here, our heads sensibly in the clouds we look down on coasting birds that in their turn look down on brown, frozen fields broken by bright green bands painted between pencil lines of graphic earth. The shaggy, wild heads appear over the ridge of the next rampart and we don't stand a chance: no way, not ever, out of this skirmish, to reach the middle. A beech tree broken and fallen builds a bridge between outer and inner. This is it. First circle completed but the air bites with hints of more snow to come as we descend into the first ditch and the sky always changing against the curving horizon.