On Generation and corruption
moist, and 'the dry' which is opposed to it will derive from the
primary dry. Again (ii) the 'moist' and the solidified derive in the
same way from the primary pair. For 'moist' is that which contains
moisture of its-own deep within it ('sodden' being that which is
deeply penetrated by foreign mosture), whereas 'solidigied' is that
which has lost this inner moisture. Hence these too derive from the
primary pair, the 'solidified' from the dry and the 'solidified'
from the dry the 'liquefiable' from the moist.
It is clear, then, that all the other differences reduce to the
first four, but that these admit of no further reduction. For the
hot is not essentially moist or dry, nor the moist essentially hot
or cold: nor are the cold and the dry derivative forms, either of
one another or of the hot and the moist. Hence these must be four.
The elementary qualities are four, and any four terms can be
combined in six couples. Contraries, however, refuse to be coupled:
for it is impossible for the same thing to be hot and cold, or moist
and dry. Hence it is evident that the 'couplings' of the elementary
qualities will be four: hot with dry and moist with hot, and again
cold with dry and cold with moist. And these four couples have
attached themselves to the apparently 'simple' bodies (Fire, Air,
Water, and Earth) in a manner consonant with theory. For Fire is hot
and dry, whereas Air is hot and moist (Air being a sort of aqueous
vapour); and Water is cold and moist, while Earth is cold and dry.
Thus the differences are reasonably distributed among the primary
bodies, and the number of the latter is consonant with theory. For all
who make the simple bodies 'elements' postulate either one, or two, or
three, or four. Now (i) those who assert there is one only, and then
generate everything else by condensation and rarefaction, are in
effect making their 'originative sources' two, viz. the rare and the