IV
The cardinal factor, however, in causing time to
become a concept of primary importance was the
spread of Christianity. Its central doctrine of the Cruci-
fixion was regarded as a unique event in time not
subject to repetition and so implied that time must be
linear rather than cyclic. Before the rise of Christianity
only the Hebrews and Zoroastrian Iranians appear to
have developed teleological conceptions of the uni-
verse implying that history is progressive. The histori-
cal view of time, with particular emphasis on the
nonrepeatability of events was, however, the very es-
sence of Christianity. The contrast with the Hebrew
view is clearly brought out in the Epistle to the He-
brews (9:25-26): “Nor yet that he should offer himself
often, as the high priest entereth into the holy place
every year with the blood of others; For then must
be often have suffered since the foundation of the
world; but now once in the end of the world hath he
appeared to put away sin by the sacrifice of himself.”
Nevertheless, the idea of denominating the years
serially in a single era count, such as the Olympic
dating from 776 B.C. and the Seleucid from 311 B.C.,
did not originate in the Christian era until it was
introduced by Dionysius Exiguus in A.D. 525, and the
B.C. sequence extending backwards from the birth of
Christ was only introduced in the latter part of the
seventeenth century. In medieval Europe, as in me-
dieval China, ancient Greece, and pre-Columbian
America, time was not conceived as a continuous
mathematical parameter but was split up into separate
seasons, divisions of the Zodiac, and so on, each exert-
ing its specific influence. In other words, magical time
had not yet been superseded by scientific time. More-
over, throughout the whole medieval period, there was
a conflict between the cyclic and linear concepts of
time. The scientists and scholars, influenced by astron-
omy and astrology, tended to emphasize the cyclic
concept. The linear concept was fostered by the mer-
cantile class and the rise of a money economy. For,
as long as power was concentrated in the ownership
of land, time was felt to be plentiful and was associated
with the unchanging cycle of the soil. With the circu
lation of money, however, the emphasis was on mo-
bility. In other words, men were beginning to believe
that “time is money” and that one must try to use it
economically and thus time came to be associated with
the idea of linear progress.
In the course of the fourteenth century many public
mechanical clocks that rang the hours were set up in
European towns. They were very expensive and, de-
spite their lack of accuracy, they were a source of pride
to the citizens. Clocks were made with curious and
complicated movements. It was easier to add wheels
than to regulate the escapement. Moreover, in view
of the general belief that a correct knowledge of the
relative positions of the heavenly bodies was necessary
for the success of most human activities, many early
clocks involved elaborate astronomical representations.
The most celebrated was the Strasbourg clock set up
in 1350, but the most elaborate was the astronomical
domestic clock made at about the same time by Gio-
vanni de' Dondi. From about 1400 there are records
of the purchase of domestic clocks by royalty, but until
the latter part of the sixteenth century these clocks
were very rare.
Although medieval scholars were not concerned with
machines, they became more and more interested in
clocks, particularly because of their connection with
astronomy. Already in the fourteenth century Nicole
Oresme (1323-82), Bishop of Lisieux, likened the uni-
verse to a vast mechanical clock created and set mov-
ing by God so that “all the wheels move as harmoni-
ously as possible.” The great leaders of the scientific
revolution of the seventeenth century were much con-
cerned with horological questions and metaphors.
Early in the century Kepler specifically rejected the
old quasi-animistic magical conception of the universe
and asserted that it was similar to a clock, and later
the same analogy was drawn by Robert Boyle and
others. Thus the invention of the mechanical clock
played a central role in the formulation of the mecha-
nistic conception of nature that dominated natural
philosophy from Descartes to Kelvin. An even more
far-reaching influence has been claimed for the me-
chanical clock by Lewis Mumford who has argued that
it “dissociated time from human events and helped
create the belief in an independent world of mathe-
matically measurable sequences: the special world of
science” (Technics and Civilization, p. 15).
Nevertheless, this development was for a long time
hampered by the lack of any accurate mechanical
means for measuring small intervals of time. Thus, in
his famous experiments on the rate of fall of bodies
rolling down an inclined plane, Galileo measured time
by weighing the quantity of water which emerged as
a thin jet from a vessel with a small hole in it. It is
not surprising that he refrained as far as possible from
giving a concrete value for the acceleration due to
gravity and that when he did state a value it was less
than half the correct amount. The construction of
precision timekeepers was stimulated by the needs of
astronomy and navigators, and they contributed to the
development of science itself.
