Table Of ContentTHE PHYSICAL WORLD OF LATE ANTIQUITY
By the same Author
THE PHYSICAL WOPLD OF THE GREEKS
PHYSICS OF THE STOICS
S. SAMBURSKY
THE PHYSICAL
WORLD OF
LATE ANTIQUITY
Princeton University Press
Princeton, New Jersey
Published by Princeton University Press, 41 William Street,
Princeton, New Jersey 08540
Copyright (E) 1962 by S Sambursky
All rights reserved
First Princeton Paperback printing, 1987
LCC
ISBN 0-691-08476-9
ISBN 0-691-02410-3 (pbk.)
Reprinted by arrangement with Routledge &• Kegan Paul Ltd., Great
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CONTENTS
PREFACE page vii
INTRODUCTION xi
I SPACE AND TIME
ι. Absolute and relative space ι
2. Absolute and relative time 9
3. Time and change 14
II MATTER
1. The mechanistic theory: conceptual developments 2 χ
2. Plato's geometrical theory and Aristotle's objections 29
3. The qualitative theory 34
4. Neo-Platonic revival of the geometrical theory 44
III SUBLUNAR MECHANICS
1. The laws of motion 62
2. The impetus 70
3. Natural motion and weight 76
4. Motion of continuous masses 89
5. Perturbations 93
IV MODES OF PHYSICAL ACTION
1. Local action and action at a distance 99
2. Potentiality and fitness 104
3. Actualityandaction 110
4. The use of philosophical principles 117
V CELESTIAL PHYSICS
1. Xenarchus against the aether 122
2. Ptolemy: the struggle for a unitary picture 133
3. Proclus and the Ptolemaic system 145
y
CONTENTS
VI THE UNITY OF HEAVEN AND EARTH
1. John Philoponus and his conception o f the universe 154
2. Philoponus1 arguments and Simplicius objections 158
3. God and Nature 166
NOTES 176
SOURCES 179
INDEX OF PASSAGES QUOTED 181
GENERAL INDEX 185
vi
PREFACE
THE present book, in a way a continuation of my two earlier
ones, describes the development of scientific conceptions and
theories in the centuries following Aristotle until the close of
antiquity in the sixth century A.D. From the copious literature of
that period, and the works of the Aristotelian commentators in
particular, I have selected and interpreted texts which are of
interest for the comparative history of scientific ideas, with special
emphasis on the epistemological foundations of physical theories.
The sequence of the chapters is determined by methodological
considerations, but each chapter is largely independent of the
others, dealing with one special aspect of the subject. The material
contained in some of the chapters is an extension of lectures
which I gave in the spring of i960 at universities in England and
the U.S.A.
Relatively little has been published on the history of scientific
doctrines in the later centuries of antiquity, with the exception of
the relevant chapters in P. Duhem's comprehensive work Le
Systeme du Monde, which appeared about fifty years ago. I
cherish the somewhat immodest hope that the present book may
help to change for the better the attitude of neglect towards later
antiquity still shared by many classical scholars and scientists
alike. It was a period which retained strong intellectual bonds
with the classical past but which, in its mode of thought, was akin
to a much later age.
Professor S. Pines of the Hebrew University has read the
manuscript and made many helpful comments, Dr. C. Broude
has corrected the style, and my wife has given much care to the
preparation and typing of the manuscript. To all of them I offer
my sincerest thanks.
INTRODUCTION
I
N the history of Greek science one has to distinguish between
two parallel developments: on the one hand scientific achieve
ments in the technical sense, comprising all the factual discoveries
and inventions in mathematics, astronomy and the physical and
biological sciences, and on the other hand scientific thought, aim
ing at the formation of comprehensive theories and the philoso
phical foundation of a scientific world-picture. The development
of science proper, taken in the first sense, gathered momentum in
a relatively short period and reached its apex in the third and
second centuries B.C. From then on, it slowly declined and, with
few exceptions, faded out after the second century A.D. At that
time the two greatest scientific achievements of the Greeks—
geometry and astronomy—were practically accomplished, and
the same can be said of their discoveries in acoustics, optics and
mechanics.
Scientific thought, however, continued with uninterrupted
vigour from the times of the Milesian philosophers around 550
B.C. until the last Neo-Platonists in the middle of the sixth century
A.D. During these eleven hundred years, hypotheses on the
creation and structure of the universe were produced, theories on
the nature of space, time and matter discussed, scientific concepts
formed and analysed from an epistemological and purely logical
point of view, and inquiries made into such problems as causality
and determinism and the nature of physical action. The main
contributors to scientific thinking were not the great scientists
themselves, like Euclid, Archimedes, Apollonius and Hipparchus,
but rather the founders or representatives of philosophical sys
tems of thought, men like Democritus, Plato, Aristotle, Epicurus
and Chrysippus, and in late antiquity the Neo-Platonists. It is
worth remembering that of these men only Aristotle, who made
the most important contribution to the picture of the cosmos, was
also an outstanding scientist, in the field of biology.
Thus in antiquity the two types of scientific activity did not
merge into a single stream as they have gradually done in modern
ix
INTRODUCTION
times, since Galileo and Newton. From the seventeenth century
on, systematic experimentation and the mathematization of
physics were the two main factors which in the physical sciences
led to the crystallization of a more or less consistent system of
knowledge out of an ever-growing wealth of factual discoveries
and the various attempts at a theoretical foundation. To an ever-
increasing degree, leading scientists themselves share in the
synthesis of the picture of the physical world, having taken the
lead from the philosophers in the epistemological investigation of
scientific concepts. In ancient Greece the scope of experimental
research remained restricted because the Greeks, with very few
exceptions, failed to take the decisive step from observation to
systematic experimentation. Thus hardly any links were formed
between the few branches of science which developed, and they
did not expand sufficiently to produce a coherent and inter
dependent system. The body of scientific knowledge in antiquity
did not reach the critical mass necessary to induce the great
scientists themselves to make an attempt at the construction of a
theoretical framework which would unite the results of their own
research and that of other branches of science.
In view of these serious shortcomings it is astonishing to what
an extent arbitrariness was reduced by the extraordinary flair of
the Greek mind for rational speculation in the right direction.
Greek scientific thinking elaborated in a qualitative, non-mathe-
matical way two main patterns which became precursors of the
basic trends in modern physical thought: continuum theory and
atomism. The scientific world-picture of Aristotle, an all-embra
cing theory loosely related to experience and built on a few
theoretical assumptions which were derived in part from earlier
conceptions, became dominant in Greek and medieval thought.
In fact, it is one of the three major world views in the history of
science, being followed after a long interval by that of Newton
which has since been replaced by that of relativity and quantum
physics. Although the Aristotelian picture of the universe out
lived its ancient rival systems, several of its conceptions and
assumptions underwent notable modifications during the more
than eight hundred years from Aristotle until the closure of the
Academy in Athens by Justinian.
These changes, the subject of the present book, are of great
significance for the history of science, for several reasons. In the
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