ased than that which has unequal
sides; and of the compound figures which are formed out of either, the
plane equilateral quadrangle has necessarily a more stable basis than
the equilateral triangle, both in the whole and in the parts. Wherefore,
in assigning this figure to earth, we adhere to probability; and to
water we assign that one of the remaining forms which is the least
moveable; and the most moveable of them to fire; and to air that which
is intermediate. Also we assign the smallest body to fire, and the
greatest to water, and the intermediate in size to air; and, again, the
acutest body to fire, and the next in acuteness to air, and the third
to water. Of all these elements, that which has the fewest bases must
necessarily be the most moveable, for it must be the acutest and most
penetrating in every way, and also the lightest as being composed of the
smallest number of similar particles: and the second body has similar
properties in a second degree, and the third body in the third degree.
Let it be agreed, then, both according to strict reason and according to
probability, that the pyramid is the solid which is the original element
and seed of fire; and let us assign the element which was next in the
order of generation to air, and the third to water. We must imagine all
these to be so small that no single particle of any of the four kinds
is seen by us on account of their smallness: but when many of them are
collected together their aggregates are seen. And the ratios of their
numbers, motions, and other properties, everywhere God, as far as
necessity allowed or gave consent, has exactly perfected, and harmonized
in due proportion.

From all that we have just been saying about the elements or kinds, the
most probable conclusion is as follows:--earth, when meeting with fire
and dissolved by its sharpness, whether the dissolution take place in
the fire itself or perhaps in some mass of air or water, is borne hither
and thither, until its parts, meeting together and mutually harmonising,
again become earth; for they can never take any other form. But water,
when divided by fire or by air, on re-forming, may become one part fire
and two parts air; and a single volume of air divided becomes two of
fire. Again, when a small body of fire is contained in a larger body of
air or water or earth, and both are moving, and the fire struggling is
overcome and broken up, then two volumes of fire form one volume of air;
an