Boundaries - Time's Arrow, Time's Cycle: Myth and Metaphor in the Discovery of Geological Time - page 194

plex historical phenomena requires absolutely—while other favored
dichotomies, like evolution versus creation, cannot be so fruitful because the
ends don't balance, at least in the sense that for certain classical issues (the
history of life for example), one side is simply wrong, and therefore drops
from intellectual interest, though not necessarily from political clout.
Evolution consumed creation (in the strict version of all species fashioned ex
nihilo on a young earth), but arrows and cycles need each other if we ever
hope to grasp the meaning of history. Arrows and cycles are "eternal
metaphors."
Time's arrow expresses the profundity in a style of explanation that many
people find disappointing, or maximally unenlightening—the argument that
"just history" underlies this or that phenomenon (not a law of nature, or some
principle of timeless immanence). The essence of time's arrow lies in the
irreversibility of history, and the unrepeatable uniqueness of each step in a
sequence of events linked through time in physical connection—ancestral ape
to modern human, sediments of an old ocean basin to rocks of a later
continent. Abstracted parts of any totality may record the predictable (and
repeatable) operation of nature's laws, but the details of an entire
configuration are "just history" in the sense that they cannot arise again, and
that another set of antecedents would have yielded a different outcome.
We may judge such a statement obvious and banal today, but it has often
acted as the primary agent of major conceptual shift when history extended
its realm, or when we learned to grasp history as contingent complexity,
rather than preplanned harmony. For example, many popular pre-Darwinian
taxonomic schemes were rooted in numerology—the grouping of all
organisms into wheels of five, for example, with exact correspondences
between spokes of all wheels—so that fishes on the wheel of vertebrates
correspond with echinoderms on the wheel of all animals because both live
exclusively in the sea, or mammals on the vertebrate circle with all
vertebrates on the inclusive wheel, because both are the pinnacles of their
respective systems. Such a scheme, proposed by William Swainson and other
early nineteenth-century "quinarians" (see Fig