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PA T R IC IA F. O ’G R A D Y , Thales o f Miletus: The Beginnings o f
Western Science an d Philosophy (Hants: A shgate Publishing Limited,
2002); xxii plus 310; ISBN 0 7546 0533 7; £49.50.
W ith Patricia O ’G rad y 's Thales o f Miletus w e are fortunate to have
the first book-length treatm ent o f the greatest o f the seven ancient G reek
Sages. W hen textual m aterial is severely lim ited, as it is for Thales, an
author m ust neither shy aw ay from conjecture nor shirk a corresponding
depth o f critical analysis.
O ’G rad y ’s extensively researched and
balanced presentation fully m eets these requirem ents. M ore than this,
though, as T hales’ accom plishm ents unfold throughout the w ork she
conveys her ow n adm iration for him as the founder o f W estern science
and philosophy, and she inspires that sam e sense in her reader.
A lthough the doxographical tradition is in no w ay neglected,
A ristotle rem ains the central source for this study. C hapter Two
investigates A ristotle’s possible sources for his discussions o f Thales,
w hile C hapter Three analyses the conceptual fram ew ork in w hich
A ristotle introduces T hales’ ‘w atery principle,’ and carefully
distinguishes the varying degrees o f confidence, from assertion to
caution, that A ristotle applies to his statem ents. Contrary to the claim s o f
w riters such as H arold C hem iss and J.B. M cD iarm id, w ho hold that
A ristotle ‘often m isrepresents the doctrines o f his predecessors in order
to support his ow n particular opinions’ (42), O ’G rady concludes:
In relation to his reporting o f Thales I believe that
A ristotle presented an accurate claim , and that he
presented it w ith confidence. It w as only when
A ristotle attem pted to provide the reasons for the
opinions that Thales held, and for the theories that
he proposed, that he som etim es displayed caution.
(42)
W hile C hapter Four review s the biological, m eteorological and
geological observations that T hales’ m ight have taken as evidence for
his claim that the first principle is water, the next chapter m arks a clear
disjunction betw een ancient G reek m ythology and Thalean scientific
speculation. A lthough A ristotle recorded a contem porary opinion that
ancient theological speculation agreed w ith Thales in assigning w ater as
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the prim ary entity, A ristotle him self had no hesitation in recognising
Thales as the first natural philosopher.
O ’G rady agrees with his
assessm ent, concluding that
Thales broke aw ay from the tired explanations. He
proposed a basic m aterial substance, identified a
source o f energy to account for change,
hypothesized that w ater supported earth, and that
earthquakes w ere caused by the rocking o f the
earth. . . . Thales made a distinct break from the
m ythical w ays o f describing the universe to a
scientific explanation. It was the beginning o f
science. (82)
W e see this disjunction again in C hapter Seven, w here O ’Grady
untangles the conflicting statem ents o f the ancient writers, from
A ristotle to Stobaeus, about T hales’ understanding o f the soul. She
suggests, plausibly, that A ristotle’s attribution to Thales o f the view that
‘everything is full o f g ods' (D e Anima 41 l a8 ) has its probable source in
Plato (e.g.. Laws 899a-b, w here souls are said to be gods), and that
T h ales’ view should not be understood in any religious sense. Rather,
she concludes that ‘T h ales's [v/c] view w as o f a universe entirely
en souled’ (123).
T hales’s [.v/c] hypothesis was corroborated, and
perhaps initiated, by his observation o f the pow er
that exhibited [.v/c] in M agnesian stone and amber.
To extrapolate from his recognition that m agnets
and am ber are endow ed with a potential force, an
im m aterial principle o f m ovem ent and life, to a
scientific hypothesis that had all things, the entire
cosm os, perm eated with a universal life force, was
a piece o f original and brilliant science ( 122).
A lthough giving A ristotle his rightful place as our prim e source o f
inform ation about Thales. O 'G rad y is certainly not blindly beholden to
A ristotle’s opinions. In C hapter Six, she argues that A ristotle may have
m isunderstood T hales’ claim about earth resting on water.
W hile
A ristotle takes Thales to be saying that the entire Earth floats on water.
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and criticises his theory on this basis, the author suggests that Thales is
m ore likely to be saying that the land m asses float on w ater sim ilarly to
the way that pieces o f w ood do. O ’G rady m akes this possibility
plausible through consideration o f the genuine phenom enon o f ‘floating
m ats’ o f accum ulated debris, vegetation and sedim ent, som e o f which
w ere apparently know n in classical antiquity. O ne w onders, how ever, if
this conjecture is too generous to Thales, given that the broader context
(D e Caelo 11.13) in w hich it is discussed by A ristotle (our only source
for T h ales’ speculation on this topic) does appear to be the Earth as a
w hole.
C hapter Eight, N ew Ideas about the Cosm os, is outstanding. Here
the author paints an inspiring portrait o f Thales as the first astronom ical
scientist. W e read o f T hales’ com prehension o f the phenom ena o f lunar
and solar eclipses and his fam ous prediction o f the solar eclipse that
occurred on 28 M ay, 585 BC. D elving into the history o f ancient
astronom y, O ’G rady show s that Thales could not have predicted this
eclipse using the so-called Saros or Exeligm os eclipse cycles that
scholars favour as his m ethod. Instead, she argues, it is likely that
Thales knew o f and utilised a lunar eclipse-solar eclipse period o f 2 3 ‘/2
months, derived from data accum ulated through observations. W e also
learn o f T hales’ fixing the tim es o f the solstices, and o f how he might
have achieved this, his determ ination o f the diam eters o f the sun and
moon, and o f his setting the length o f the solar year at 365 days.
Thales em erges as a pioneering m athem atician in C hapter Ten.
A lthough Thales probably travelled to Egypt and thus learned Egyptian
m ensuration, certain m ore abstract geom etrical discoveries or ‘p ro o fs’
w ere attributed to him. E.g., Proclus, in his com m entary on Euclid,
claim ed that it w as Thales w ho first show ed that a diam eter o f a circle
bisects it and that the base angles o f an isosceles triangle are equal.
A lthough T hales’ m athem atical w ork w ould have lacked the
dem onstrative structure o f later G reek m athem atics, O ’G rady suggests
that his discoveries could be granted the status o f inductive proofs.
The only slightly disappointing section o f this book— and this is a
m inor point— is in the penultim ate chapter, w here the author evaluates
T hales’ scientificity, in part, by criteria o f tw entieth-century scepticism ,
nam ely those o f K arl P opper’s falsificationist philosophy o f science. In
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my view, T hales’ quest for w hat is ultim ately real m arked him as a
philosopher, and his quest for natural explanatory causes qualified him a
scientist, w ithout the need to appeal to an anachronistic standard,
especially one that has few adherents am ongst today’s philosophers o f
science. T h ales’ achievem ents, w hich com e alive through O ’G rady’s
com prehensive and sym pathetic presentation, are am ple justification for
calling him the first ancient G reek scientist and philosopher.
One final note: the book itself and each o f its chapters conclude
with convenient sum m aries, and there are two inform ative appendices,
one on T hales’ travels and one on the seven Sages o f A ncient Greece.
Stuart Johns
U niversity o f A uckland
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