Physics 145
fact is that everything which is nourished and grows contains within
itself a large measure of heat, without which these things could neither
be nourished nor grow. For everything which is warm and fiery is set
going and kept in motion by its own characteristic motion; but that which
is nourished and grows makes use of a certain definite and regular motion;
as long as this remains in us our power of sense-perception and life
remains, but when this heat is cooled and extinguished, then we ourselves
die and are extinguished. 24. On this point, Cleanthes also uses these
arguments to show how great is the power of heat in every body. He
says that there is no food which is so heavy that it cannot be digested^28
within a night and a day, and even the residues of the food, which are
naturally eliminated, contain heat. Moreover, the veins and arteries do
not cease to pulsate with a certain flame-like motion; and it has often
been observed that when some animal's heart is removed it continues to
beat as rapidly as a flickering flame. Therefore, everything which lives,
whether an animal or a vegetable, lives because of the heat contained
within it. From this one should understand that the nature of heat has
within itself the power of life which penetrates the entire cosmos.- This will be easier to see if we give a more detailed account of
this all-pervasive fiery stuff as a whole. All parts of the cosmos (though
I will only deal with the most important parts) are supported and sustained
by heat. This can be seen first in the nature of earth. For we see that
fire is produced when stones are struck or rubbed together, and when a
hole has just been dug we see 'the warm earth steaming'; and warm water
is drawn even from spring-fed wells, especially in winter, because the
hollow parts of the earth contain a great deal of heat and in winter [the
earth] is denser and so confines the heat which is native to it more tightly. - It could be shown, by a long discourse and many arguments, that all
the seeds which the earth receives and all the plants which are generated
from her and which she holds rooted in her are born and grow because
of her temperate heat.
And that heat is also blended with water is shown first of all by the
fluidity of water, which would neither be frozen by the cold nor solidified
into snow and frost if it did not also dissolve and liquify itself when heat
is added. Thus moisture hardens when it is affected by the blasts of the
north wind and other sources of cold, and in turn is softened when
warmed and is [even] dried up by heat. Even the seas, when tossed by
the winds, warm up to such an extent that one can easily see that heat
is enclosed in these vast bodies of water; and one must not suppose that
the warmth in question comes from some external and extraneous source, - The word literally means 'cooked'; hence the point about heat.