Ser Perth shuddered slightly. "My greatest wish is that I die before I
learn. In your world, had you discovered that there were such things as
elements? That is, basic substances which in combination produce--"

"Of course," Dave interrupted.

"Good. Then of the four elements--" Dave gulped, but kept silent, "--of
the four elements the universe is built. Some things are composed of a
single element; some of two, some of three. The proportions vary and the
humors and spirits change but all things are composed of the elements.
And only the sky is composed of all four elements--of earth, of water,
of fire and of air--in equal proportions. One part each, lending each
its own essential quality to the mixture, so that the sky is solid as
earth, radiant as fire, formless as water, insubstantial as air. And the
sky is cracking and falling, as you have seen for yourself. The effects
are already being felt. Gamma radiation is flooding through the gaps;
the quick-breeding viruses are mutating through half the world, faster
than the Medical Art can control them, so that millions of us are
sneezing and choking--and dying, too, for lack of antibiotics and proper
care. Air travel is a perilous thing; just today, a stratosphere roc
crashed head-on into a fragment of the sky and was killed with all its
passengers. Worst of all, the Science of Magic suffers. Because the
stars are fixed on the dome of the sky. With the crumbling of that dome,
the course of the stars has been corrupted. It's pitiful magic that can
be worked without regard to the conjunctions of the planets; but it is
all the magic that is left to us. When Mars trines Neptune, the Medical
Art is weak; even while we were conjuring you, the trine occurred. It
almost cost your life. And it should not have occurred for another seven
days."