the comet is formed independently it falls behind the motion of the
universe, like the rest of the terrestrial world. It is this fact,
that a comet often forms independently, indeed oftener than round
one of the regular stars, that makes it impossible to maintain that
a comet is a sort of reflection, not indeed, as Hippocrates and his
school say, to the sun, but to the very star it is alleged to
accompany-in fact, a kind of halo in the pure fuel of fire.
As for the halo we shall explain its cause later.
The fact that comets when frequent foreshadow wind and drought
must be taken as an indication of their fiery constitution. For
their origin is plainly due to the plentiful supply of that secretion.
Hence the air is necessarily drier and the moist evaporation is so
dissolved and dissipated by the quantity of the hot exhalation as
not readily to condense into water.-But this phenomenon too shall be
explained more clearly later when the time comes to speak of the
winds.-So when there are many comets and they are dense, it is as we
say, and the years are clearly dry and windy. When they are fewer
and fainter this effect does not appear in the same degree, though
as a rule the is found to be excessive either in duration or strength.
For instance when the stone at Aegospotami fell out of the air-it
had been carried up by a wind and fell down in the daytime-then too
a comet happened to have appeared in the west. And at the time of
the great comet the winter was dry and north winds prevailed, and
the wave was due to an opposition of winds. For in the gulf a north
wind blew and outside it a violent south wind. Again in the archonship
of Nicomachus a comet appeared for a few days about the equinoctial
circle (this one had not risen in the west), and simultaneously with
it there happened the storm at Corinth.
That there are few comets and that they appear rarely and outside
the tropic circles more than within them is due to the motion of the
sun and the stars. For this motion does not only cause the hot
principle to be secreted but also dissolves it when it is gathering.