Boundaries - Time's Arrow, Time's Cycle: Myth and Metaphor in the Discovery of Geological Time - page 200

clarity of insight. They do not blend, but dwell together in tension and fruitful
interaction.
When Ritta-Christina (Figure 5.9), the Siamese twin girls of Sardinia, died in
1829, the pundits of her day debated at great length and to no avail the
pressing issue of whether she had been one or two people. The issue could
not be resolved because it has no answer expressed in terms these pundits
sought. Their categories were wrong or limited. The boundaries between
oneness and twoness are human impositions, not nature's taxonomy. Ritta-
Christina, formed from a single egg that failed to divide completely in
twinning, born with two heads and two brains but only one lower half, was in
part one, and in part two—not a blend, not one-and- a-half, but an object
embodying the essential definitions of both oneness and twoness, depending
upon the question asked or the perspective assumed.
The same tension and multiplicity have pervaded our Western view of time.
Something deep in our tradition requires, for intelligibility itself, both the
arrow of historical uniqueness and the cycle of timeless immanence—and
nature says yes to both. We see this tension in Burnet's frontispiece, in Lyell's
method for dating the Tertiary, and in Hampton's Throne. We find it etched
in pictorial form into the iconography of any medieval cathedral in Europe,
where the arrow of progressive history passes from Old Testament lore on
the dark north side, to resurrection and future bliss on the sunlit south. Yet
we also see the cycle within the arrow. A set of correspondences—like
Burnet's globes and Hampton's symmetries—teaches us that each event of
Christ's life replays an incident in the previous cycle of Old Testament
history. We see, in short, Burnet's resolution of rolling wheels. Each moment
of the replay is similar as a reflection of timeless principles, and different
because time's wheel has moved forward.
In the twelfth-century stained glass of Canterbury (Figure 5.10), Lot's wife
turns into a pillar of salt, her whiteness contrasting starkly with the glittering
colors of Sodom and Gomorrah in flames. In the corresponding panel of the
second cycle, angels visit the wise