uum,' the finer and more subtle particles of the lighter
elements, such as fire and air, are thrust into the interstices of the
larger, each of them penetrating according to their rarity, and thus
all the elements are on their way up and down everywhere and always
into their own places. Hence there is a principle of inequality, and
therefore of motion, in all time.

In the next place, we may observe that there are different kinds of
fire--(1) flame, (2) light that burns not, (3) the red heat of the
embers of fire. And there are varieties of air, as for example, the pure
aether, the opaque mist, and other nameless forms. Water, again, is
of two kinds, liquid and fusile. The liquid is composed of small and
unequal particles, the fusile of large and uniform particles and is more
solid, but nevertheless melts at the approach of fire, and then spreads
upon the earth. When the substance cools, the fire passes into the air,
which is displaced, and forces together and condenses the liquid mass.
This process is called cooling and congealment. Of the fusile kinds the
fairest and heaviest is gold; this is hardened by filtration through
rock, and is of a bright yellow colour. A shoot of gold which is darker
and denser than the rest is called adamant. Another kind is called
copper, which is harder and yet lighter because the interstices are
larger than in gold. There is mingled with it a fine and small portion
of earth which comes out in the form of rust. These are a few of the
conjectures which philosophy forms, when, leaving the eternal nature,
she turns for innocent recreation to consider the truths of generation.

Water which is mingled with fire is called liquid because it rolls
upon the earth, and soft because its bases give way. This becomes more
equable when separated from fire and air, and then congeals into hail or
ice, or the looser forms of hoar frost or snow. There are other waters
which are called juices and are distilled through plants. Of these we
may mention, first, wine, which warms the soul as well as the body;
secondly, oily substances, as for example, oil or pitch; thirdly,
honey, which relaxes the contracted parts of the mouth and so produces
sweetness; fourthly, vegetable acid, which is frothy and has a burning
quality and dissolves the flesh. Of the kinds of earth, that which is
filtered through water passes into stone; the water is broken up by the
earth and escapes in the form of air--this in turn presses u