It takes between three and six hours to make each snowball, depending on snow quality. Wet snow is quick to work with but also quick to thaw, which can lead to a tense journey to the cold store.

A stone is ingrained with geological and historical memories.

The difference between a theatre with and without an audience is enormous. There is a palpable, critical energy created by the presence of the audience.

It's frightening and unnerving to watch a stone melt.

The first stone was just tried in the spirit of experimentation. The opening of the stone was far more interesting than the drawing that I had done on it.

The hardened mass of liquid stones had much stronger qualities than those which had simply torn. The skin remained a recognisable part of the molten stone.

It takes between three and six hours to make each snowball, depending on snow quality. Wet snow is quick to work with but also quick to thaw, which can lead to a tense journey to the cold store.

Stones are checked every so often to see if any have split or at worst exploded. An explosion can leave debris in the elements so the firing has to be abandoned.

Even in winter an isolated patch of snow has a special quality.

I did tests on small stones before collecting and committing myself to the larger ones.

The first snowball I froze was put in my mother's deep freeze when I was in my early 20s.

Winter makes a bridge between one year and another and, in this case, one century and the next.

A snowball is simple, direct and familiar to most of us. I use this simplicity as a container for feelings and ideas that function on many levels.

I have walked around the same streets so many times, and then seen a place that had been hidden to me. I now know the sites in a way that makes me think I could have made better use of the connections between place and snowball.

Some of the snowballs have a kind of animal energy. Not just because of the materials inside them, but in the way that they appear caged, captured.

People do not realise that many of my works are done in urban places. I was brought up on the edge of Leeds, five miles from the city centre-on one side were fields and on the other, the city.

As with all my work, whether it's a leaf on a rock or ice on a rock, I'm trying to get beneath the surface appearance of things. Working the surface of a stone is an attempt to understand the internal energy of the stone.

The reason why the stone is red is its iron content, which is also why our blood is red.

Three or four stones in one firing will all react differently. I try to achieve a balance between those that haven't progressed enough and those about to go too far.

I'm cautious about using fire. It can become theatrical. I am interested in the heat, not the flames.

The early firings contained many stones.

Ideas must be put to the test. That's why we make things, otherwise they would be no more than ideas. There is often a huge difference between an idea and its realisation. I've had what I thought were great ideas that just didn't work.

Not being able to touch is sometimes as interesting as being able to touch.

I enjoy working in a quiet and subversive way.

Occasionally I have come across a last patch of snow on top of a mountain in late May or June. There's something very powerful about finding snow in summer.

I have worked with this red all over the world - in Japan, California, France, Britain, Australia - a vein running round the earth. It has taught me about the flow, energy and life that connects one place with another.

The stones tear like flesh, rather than breaking. Although what happens is violent, it is a violence that is in stone. A tear is more unnerving than a break.

The relationship between the public and the artist is complex and difficult to explain. There is a fine line between using this critical energy creatively and pandering to it.

I am not a performer but occasionally I deliberately work in a public context. Some sculptures need the movement of people around them to work.

Abandoning the project was incredibly stressful after having gone through the process of building the room, installing the kiln, collecting the stones, sitting with the kiln day and night as it came to temperature, experiencing the failures.

My art is an attempt to reach beyond the surface appearance. I want to see growth in wood, time in stone, nature in a city, and I do not mean its parks but a deeper understanding that a city is nature too-the ground upon which it is built, the stone with which it is made.

People also leave presence in a place even when they are no longer there.

Fire is the origin of stone.By working the stone with heat, I am returning it to its source.

I soon realised that what had happened on a small scale cannot necessarily be repeated on a larger scale. The stones were so big that the amount of heat required was prohibitively expensive and wasteful.

Once the fired stone is out of the kiln, it is still possible to mentally reconstruct it in its original form.

Confrontation is something that I accept as part of the project though not its purpose.

Snow provokes responses that reach right back to childhood.

Photography is a way of putting distance between myself and the work which sometimes helps me to see more clearly what it is that I have made.

Fire is the origin of stone. By working the stone with heat, I am returning it to its source.

Design implies a sense of mapping something out and then you follow the plan.

The essence of drawing is the line exploring space.

If you repeat something, it can become pointless. Some things can repeat and be endlessly fascinating.

I think that any sculpture is a response to its environment. It can be brought to life or put to sleep by the environment.

I suppose, in a way, this has become part of my soul. It is a symbol of my life. Whatever I have done that really matters, I've done wearing it. When the time comes, it will be in this that I journey forth. What greater honor could come to an American, and a soldier?

The feeling remains that God is on the journey, too.

Every book is a new journey. I never felt I was an expert on a subject as I embarked on a project.

I've been pleased to work with so many wonderful stars through the years. This has been an amazing journey. I hope it continues.

In my subconscious, my books were part of a single emotional journey.

But even if I'm left high and dry at the end of this wild journey, just taking it is a great feeling.