The Four
Elements in Greek Cosmology
Greek
philosophy supposed the Universe to comprise four elements: Fire, Water,
Earth, and Air. Air was originally supposed to
be a component of the Æther [ether, not to be
confused with the gas], that which was present in the Universe
in the absence of the other three. Empedocles referred
to these as "roots" (rhizomata, ῥιζώματα), and proved that Air was a
separate element by showing that an 'empty' glass filled (that
is, one filled with 'air') inverted into a bowl of water did
not immediately fill with water, but retained a constant
volume of air. Notice that this shows by experiment that
Air is something, rather than nothing.
Empedocles also demonstrated that the amount of 'air' could be
measured: a glass pushed into the bowl displaced more water
the further it was inserted, and the measure of displaced
water was a measure of air. Aristotle was the first to call
these roots "elements" (stoicheion, στοιχεῖον),
the smallest unit of time on a sundial, or an indivisible
unit. The same root appears in Stoichiometry, the
branch of chemistry that deals with ratios between reactants
and products.
Note that the diagram includes multiple
paired associations and opposites, in keeping with
Aristotelian notions of dichotomy. Cold / Hot,
and Wet / Dry are paired across the
diagonals of the diagram. Water and Fire are fundamentally
contrasted: fire rises, water falls (as indicated by their
paired inverted alchemical triangles). Water is by nature wet
and cold, features it shares with Air and Earth, respectively.
Fire is a balance of hot and dry, and Air a balance of wet or
hot, according to the balance of moisture and heat as
determined by Water and Fire (cross bars on the alchemical
triangles). Earth is cold or dry, according to the Season.
Transformations of Water between solid Ice and gaseous Steam
are not well accommodated in this scheme.
The
Four Elements can also be arranged in ascending order,
from lower to higher. Earth rises out of Water,
Air is above the Earth, and the Sun (Fire)
is over all. (Al)Chemical reactions occur as the reactants try
to return to their proper place in the series.
Other cultures recognize analogous
arrangements. The Oriental I Ching (Book
of Changes) comprises 64 hexagrams,
each comprising two trigrams placed
one on the other. Each trigram comprises three lines, broken Yin
(--- ---) or unbroken Yang (-------).
As there are 23 = 8 trigrams,
there are 82 = 64
hexagrams. Divination is practiced by focused attention to a
question, then composition of six Yin / Yang
lines for the two trigrams. The oracle is consulted for the
hexagram: as the same lines may be formed in different ways, moving
or static, which adds further depth to the
divination. The trigrams represent combinations of the same
concepts of Fire, Water, Earth, & Air. For example, if
trigram 7 for Fire occurs above trigram 8
for Water, this produces hexagram 38, "Fire in the
Lake", the symbol of Revolution, used as the
title of Frances Fitzgerald's Pulitzer-Prize winning history
of Americans in Vietnam.
Many commentators have noted the analogy
between 64 in the I Ching and the Genetic Code,
the latter as obtained as 43 = 64
triplets. It is interesting that the third (uppermost) line in
any trigram has the least influence on meaning, just as the
third letter of the Genetic Code may have little (two-fold
degenerate) or no (four-fold degenerate) on the amino acid
encoded.