Marcus Aurelius Antoninus to Himself - College of Stoic Philosophers

i ORIGINS OF STOICISM xvii
tried in turn by the Ionian physicists. Thales selected
Water, the most versatile of substances, and the most
variable in form, as the prime unit of *
nature,' that is of
material being. Anaximenes gave the preference to Air,
which thought and language had so long associated with
the spirit and breath of life, and which alone met the
demand for quantitative infinity. Others turned to Fire,
and contemplating its generative heat, its ductile energies,
its incomparable mobility, found in it the truest source
and representative of nature's one inherent life. Theory
directed and quickened observation, and foundations of
science were laid in the observation of the celestial
bodies, and in the study of rarefaction, condensation,
liquefaction, congelation, and other natural processes;
but for the understanding of Stoicism the main outcome
is the fixed determination to derive the world of matter,
in spite of superficial appearances, from a single source
of being. And the Stoics, in their more mature en-
deavour to explain the Universe on a monistic basis,
pay tribute to these early cosmologists in freely em-
ploying such terms as Air, Breath, Fire, to denote that
elemental substance or spirit which pervades and under-
lies all things that are.
Nature defied these efforts to reduce its contents to
a single physical term, and the death-blow to such
endeavours was given by the genius of Heraclitus. He
propounded a more intelligible reconciliation between
the Many of sense and the One of thought. To him the
shifting panorama did not suggest kaleidoscopic states
of rest, succeeding one another as a series of abrupt
and stationary rearrangements. Being seemed rather