Greek and Medieval Thought. A definite separation
of time from its content was suggested by the early
Pythagoreans: “Time is said to come from the Un-
limited, that is from infinite space” (E. Zeller, A His-
tory of Greek Philosophy, trans. S. F. Alleyne, London
[1881], I, 468-69). While time was no longer personi-
fied, it was still reified, and this reification was another
step toward the separation of time from its concrete
sensory content. The fact that time itself was regarded—
rather illogically—as being subject to time (as “coming
from infinite space”) clearly showed the difficulties to
which this early reification of time led. On the other
hand, the fact that some early Pythagoreans identified
time with the celestial sphere, or, more likely, with
its rotating motion, indicated their incapacity to sepa-
rate time from its content. The reference to the celes-
tial sphere and its revolving motion had far-reaching
effects on the subsequent development of the concept
of time: it focussed the attention of philosophers on
the regular periodicity of the celestial motions by
which time can be measured, and thus it deepened the
distinction between the qualitative content of time and
its metrical aspects.
The correlation of time with spatial motion became
the source of the relational theory of time according
to which “time is nothing by itself” (Lucretius, De
rerum natura, I, 459f.) and cannot be separated from
concrete changes occurring in it. Finally the alleged
inseparability of time from spatial displacements
created the tendency to exaggerate the analogy be-
tween space and time and, eventually, to spatialize
time altogether and thus virtually to eliminate it; this
extreme tendency is very conspicuous in the Eleatic
school: the sphere of Parmenides is timeless because
of its exclusively spatial and, consequently, immutable
character. Similarly, Zeno's four arguments against the
reality of motion (and, implicitly, against the reality
of time) were based on the assimilation of time to a
geometrical line. According to Zeno, temporal inter-
vals are adequately symbolized by spatial segments;
both are divisible ad infinitum, and to the point-like
extremities of linear segments correspond the dura-
tionless extremities of temporal intervals—instants. The
impossibility of building motion from motionless posi-
tions, and durations from the durationless instants,
follows naturally.
Eleatism was the metaphysics of timeless Being in
its most radical form; it exerted a powerful influence
on the subsequent history of Western thought, even
though it has never reappeared in such extreme form.
In other words, time and becoming, instead of being
completely eliminated in the Eleatic fashion, retained
their existence, even though it was of an inferior and
less dignified kind than that of immutable Being. This
can be seen clearly in the atomists; although they did
not deny the reality of time and motion, they did not
include them among their first principles which, ac-
cording to them, were matter and space only.
Lucretius' view that “time is nothing in itself,” quoted
above, was an echo of Epicurus' view that time was
no more than an “accident of accidents” (σύμτωμα
σύπτωμάτον
since its existence was merely a function
of the changing configurations of atoms. This was
probably the view of the early atomists as well; ac-
cording to Sextus Empiricus, Democritus regarded time
as “an appearance presenting itself under the aspect
of day and night”; if he called time “uncreated,” he
meant by it that motion (on which, in his view, time
depended) is without beginning. With such a view of
time and with their anticipation of the law of constancy
of matter, the atomists greatly strengthened the static
and substantialist modes of thought.
The antisubstantialist trend in Greek philosophy was
represented by Heraclitus of Ephesus, a philosopher
of “becoming” par excellence. In his opposition to the
Eleatics, he went much farther than the atomists who,
while admitting the reality of motion, still retained its
immutable vehicle, i.e., substantial matter; for their
atoms remain eternally the same in the successive
positions of their trajectories. Heraclitus' denial of the
immutable vehicle of motion followed from his insis-
tence on the radical fluidity of everything and on the
irreversibility of becoming: “You cannot step twice into
the same river.” For the motion of immutable particles
Heraclitus substituted the dynamic unity of process in
which each momentary phase was continuously trans-
formed into its “opposite,” that is, into a subsequent,
qualitatively different phase. Heraclitus was apparently
aware that the continuity of change (his dynamic
“unity of opposites”) resists the usual conceptual treat-
ment and even a strict application of the law of con-
tradiction: “We step and we do not step into the same
river; we are and we are not” (frag. 81). This clearly
anticipated the future Hegelian view of becoming as
a synthesis of being and nonbeing.
Yet, Heraclitus' view was not free of spatial imagery,
which was hardly compatible with his insistence on
the qualitative aspect of time and its irreversibility.
This was shown by his belief in the Great Year, i.e.,
the periodic recurrence of all events in the same order.
This year, for Heraclitus, was equal to 10,800 years
(according to another source 18,000 years). According
to the testimony of the Stoics and of Simplicius (whose
reliability on this point has been questioned by
Friedrich Schleiermacher, Ferdinand Lasalle, John
Burnet, Geoffrey S. Kirk), it measured the period
separating two successive conflagrations in which the
old world perishes and a new one is reborn. Heraclitus'
idea of cyclical becoming was a culmination of the
early pre-Socratic views about the periodicity of the
worlds. The view of Anaximander, Anaxagoras, and
Empedocles was that the existing universe is the result
of the differentiation of the original chaos—watery,
fiery, or qualitatively undetermined—into which it
would eventually return and from which a similar
universe will emerge. In such view the successive cos-
mic cycles were similar in their general features only,
not in all their specific details; but the latter view,
upholding a complete identity of the successive cycles,
emerged soon. This was the idea of eternal recurrence
of everything which some Pythagoreans accepted,
influenced probably by their identification of time with
the circular motion of the heaven: “Everything will
eventually return in the self-same numerical order, and
I shall converse with you staff in hand, and you will
sit as you are sitting now, and so it will be in everything
else, and it is reasonable to assume that time too will
be the same” (The testimony of Eudemus of Rhodes;
cf. H. Diels and W. Kranz, Die Fragmente der
Vorsokratiker, 6th ed., Berlin [1951], 58B34). This was
also the view of Archytas of Tarentum who defined
time as “the interval of the universe.”
The subsequent development of Greek, medieval,
and modern philosophy was largely dominated by the
contrast between the timeless realm of Being and the
temporal realm of change; in this sense it was a contin-
uation of the dialogue between Parmenides and
Heraclitus. In most philosophical systems Being was
endowed with a more dignified status of the true reality
of which the temporal realm is merely a pale, shadowy
replica. For Plato, in the Timaeus, the basic reality
belongs to the timeless essences (Ideas) while the
temporal realm is that of ceaseless change, generation,
and decay; time itself is of derivative nature, being
merely a “moving image of eternity.” To this meta-
physical dichotomy of Being and Becoming, of perfec-
tion and imperfection, corresponds the epistemological
dichotomy of two kinds of knowledge—true knowledge
whose object is the immutable realm of Ideas, and mere
opinion, concerning the temporal realm. In the philos-
ophy of Aristotle the timeless Ideas of Plato were, so
to speak, compressed into one single entity—God, the
immovable source of every motion. Like Plato,
Aristotle held the relational view of time; time is
inseparable from motion for without motion (in the
broader Aristotelian sense of change) there would be
no time. But while Aristotle's Prime Mover has all the
attributes of the Eleatic One, his view of the physical
world—or at least of its sublunar part—was similar to
the view of Heraclitus. Aristotle rejected the atomistic
explanation of qualitative change and diversity by the
displacement of homogeneous and unchangeable ele-
ments; he denied the existence of atoms and of the
void, and reaffirmed the reality of qualitative change.
He viewed the four sublunar elements as mutually
transformable in a way analogous to the Heraclitean
transformation of opposites. Every such transformation,
including even change of position, implies a transition
from potentiality to actuality; only the Unmoved
Mover is exempt from this passage. In introducing the
concept of not-yet-existing possibility and in insisting
on the contingency of the future, Aristotle came very
close to the idea of an “open future,” which is the
central theme of modern process philosophy.
It must also be noted that in spite of his insistence
on the inseparability of time and motion, Aristotle was
careful enough not to identify them. Since there are
various motions of different speeds occurring simulta-
neously, “the time is absolutely the same for both”
(
Physics, IV, 14). There are thus absolutist elements in
Aristotle's view of time which vaguely foreshadow
Newton's view. This is also clear from his comment
on his own definition of time. After defining time as
the “numerical aspect of motion with respect to its
successive parts,” he raises the question whether time
can exist without the counting activity of mind; and
his answer is affirmative: time is
numerus numerabilis,
i.e., an objective reality susceptible of being counted
but independent of the act of counting, consequently
independent of the existence of the counting mind. The
sphere of the fixed stars represents the absolutely uni-
form cosmic clock by which time is measured; its
perfectly uniform rotation is, within the realm of
change, the closest imitation of the immutability of
the Prime Mover.
Aristotle apparently also accepted the idea of eternal
return of all the events, at least if we accept his
authorship of the following passage in Problemata:
“Just as the course of the firmament and each of the
stars is a circle, why should not also the coming into
being and the decay of perishable things be of such
a kind that the same things again come into being and
decay?” (The Works of Aristotle, ed. W. D. Ross, Oxford
[1923], VII, 916a). Aristotle realized that the cyclical
character of becoming would imply a relativization of
succession: if the Trojan War will inevitably recur, then
in a sense we are living “prior” to it. The author of
Problemata, however, refused to accept the ultimate
consequence of the idea of eternal recurrence: “To
demand that those who are coming into being should
always be numerically identical, is foolish” (ibid). Like
Plato, Aristotle associated the cosmic period (“the
Great Year”) not with a periodically recurring universal
conflagration, but with a return of all celestial bodies
to the same configuration. The idea of any cosmic
cataclysm was incompatible with Aristotle's belief in
the incorruptibility of the celestial clockwork.
The cyclicity of time was upheld also by the Stoics.
According to them, at the end of each cosmic cycle
the universe is dissolved into the original fire. This will
coincide with the beginning of another cycle in which
the events of the previous cycle will be reconstituted
in all their details and in the same order. But Stoics
followed Aristotle by believing that another Socrates
who will marry another Xantippe and be accused by
another Meletus will not be numerically identical with
the previous Socrates since numerical identity implies
an uninterrupted existence. Some younger Stoics, in
conceding small differences between successive recur-
rences of Socrates, gave up the circularity of becoming
in all but name. Like Aristotle, the Stoics also specu-
lated about the paradoxical nature of the present
moment; according to Plutarch, Chrysippus de-
nied the infinite divisibility of time, i.e., he accepted
the existence of temporally extended moments,
thus curiously anticipating the modern hypothesis of
“chronons.”
Although Plotinus' Ineffable One possesses all the
attributes of the Eleatic Being, he retained change and
time on the lower phenomenal level. He tried to make
the relation between the temporal and timeless level
more intelligible by his idea of emanation, i.e., by the
process of degradation by which the lower degrees of
reality proceed from the higher ones. This idea was
implicitly present in Plato's view of the realm of
change which “never truly is,” forever oscillating be-
tween Being and Nothingness. According to Plotinus,
change and time appear on the second level of ema-
nation with the World Soul in which individual souls
are contained. Unlike the Divine Intellect at the first
level of emanation, souls are unable to grasp the time-
less truth instantaneously, but only gradually, step by
step, in a laborious process of reasoning. Succession
and change are thus mere results of human inability
to grasp everything at once. As in Plato, time is “the
moving [and therefore imperfect] image of eternity”;
but “motion” is understood by him in a psychological
sense, as “movement of the soul”; without this move-
ment time would disappear (Enneads, III, 7, 12). From
this correlation of mind and time it follows that when-
ever there is time, there is mind at least in a rudi-
mentary form, and vice versa. In this feature Plotinus'
thought is near to modern temporalistic panpsychism
(Bergson, Whitehead); but by his concept of timeless
truth and by his adherence to the cyclical theory of
time he stands at the opposite pole.
The Greek dualism of the timeless realm of perfec-
tion and the changing realm of decay, with the con-
comitant contrast between timeless divine insight and
temporal (therefore incomplete) human knowledge
dominated all medieval thought, Christian, Jewish, and
Islamic. There were only a few theologians who did
not accept predestination as an inevitable consequence
of the time-transcending divine knowledge which em-
braces the totality of all successive events in one single
act—totum simul. In the thought of Saint Augustine
there were the same two trends as in Plotinus: on one
side, time was characterized as “distension of soul”
(Confessions, Book XI) and thus correlated with
psychological reality. Augustine's description of our
consciousness of time belongs to the finest and subtlest
pieces of introspective analysis. On the other hand,
again like Plotinus, he excluded time from the highest
level of Being; time was created by God with the
creation of the world:
Non in tempore, sed cum tempore
finxit Deus mundum (
De civitate Dei, XI, 5).
Saint Thomas equally stressed the immutability of
God (Summa Theologica, Qu. 9). It would seem then
only consistent for Saint Thomas to accept complete
predestination (Qu. 22, 23, 24). It was exceedingly
difficult to reconcile this view with the freedom of will
which he postulated on ethical grounds. More consis-
tent on this point were the Protestant reformers of the
sixteenth century who did not hesitate to negate free-
dom completely in the name of divine omniscience and
predestination. The Greek influence can be seen also
in the fact that some Christian thinkers, like Origen,
accepted the eternity of the world and even
metampsychosis (transmigration of souls); even Saint
Thomas was aware that the Aristotelian proof of the
Prime Mover did not imply the creation of the world
in time, the truth of which must be accepted on faith,
but cannot be proved (ibid., Qu. 46).
Even the idea of eternal return did not completely
disappear during the Middle Ages as is shown by the
decree of 1277 which threatened excommunication of
those who accepted the Neo-Platonic idea of a Great
Year lasting 36,000 years. It is true that because of the
Judeo-Christian emphasis on the irreversibility of cos-
mic and human history this doctrine was foreign to
that period: thus even Origen rejected the idea of
eternal recurrence because of its incompatibility with
human freedom, while Augustine rejected it on the
ground that the incarnation of Christ could occur only
once. Thomas Aquinas pointed out that the cyclical
view of time implies the re-creation of numerically
identical individuals—an operation which because of
its intrinsically contradictory character is even beyond
God's power. But neither Duns Scotus nor William of
Ockham shared Thomas' view. Nicolas Bonnet and
François de la Marche insisted on God's power to
restore any past motion, and consequently, any past
interval of time. Since the restoration of any past
interval of time implies the concomitant elimination
of that portion of the past which separates the re-
created interval from the present moment, this claim
was in direct opposition to Thomas' view of the
intrinsic indestructibility of the past which even God's
omnipotence is unable to change: Praeterita autem non
fuisse contradictionem implicat (Qu. 25, art. 4).
