Every moment there is a new landscape to contemplate; the sky moulds and shifts itself constantly, as if it were God's television broadcast to the world. We spend surprisingly little time trying to decipher the arrangement of clouds - we measure them and try to predict their motion, but we don't try to understand what they mean, what message they convey, because we are convinced that their pattern is chaotic, that they are the result of a process we understand but cannot predict, and conscious intent does not play a part in their construction; even the process itself is the result of another process, and another process, and so on back to the fundamental, the Big Bang. At no point is intelligent intervention required, and Occam's Razor therefore concludes that clouds cannot be the vehicle for intelligent communication. Yet a part of me wants to smash reason, and if mankind's energies were directed on a deranged, harmless, and insoluble cause, it would keep us occupied.

On the horizon I can see a cloudbank the size of the North Sea, an object floating in the air larger than any aircraft, larger still than the alien spacecraft in science fiction films, the ones that hang over cities and deliver ultimatums. Airliners are emerging from a point in front of it, growing from indistinct dots into Boeings and Airbuses and McDonnell-Douglases, on final approach to Heathrow. Against the backdrop of continent-sized clouds the aircraft seem tiny, they seem to be travelling much too slowly to stay aloft.

Some days the clouds stay the same. I can remember overcast days when the clouds did not even have a texture, they were solid grey, and it was impossible to judge distance or scale; it seemed as if I could see the screen against which the sky is usually projected.

What use are clouds at night? I would not have invented night-time clouds. I would not have thought to make them. I must push through the limits and enter the world of men.