Charles Lyell, Historian of Time's Cycle - Time's Arrow, Time's Cycle: Myth and Metaphor in the Discovery of Geological Time - page 165

We are apprehensive lest zoological periods in Geology, like artificial
divisions in other branches of Natural History, should acquire too much
importance, from being supposed to be founded on some great interruptions
in the regular series of events in the organic world, whereas, like the genera
and orders in zoology and botany, we ought to regard them as invented for
the convenience of systematic arrangement, always expecting to discover
intermediate gradations between the boundary lines that we have first drawn.
(III, 57)
Third—and this is harder to put in words—Lyell's method is quirky and
fascinating. It makes you think. It stands against all traditions of the field,
from his day to our own. Paleontologists are devoted to specifics.
Professionals become experts on particular groups at particular times; we
receive advanced training by apprenticeship to authorities, and we spend
years learning the taxonomic details of our chosen group. We expect to
resolve stratigraphic problems by using this expertise-to identify this stretch
of time because Joe the brachiopod lives there, and that interval because Jill
the bryozoan inhabits its strata.
"Charles Lyell's dream of a statistical paleontology" (the apt title of
Rudwick's fine analysis, 1978) stands against this tradition of particulars. It
applies to the quirky world of history the generality of an abstract process,
regular as the ticking of a clock (albeit with random fluctuations). Such
marriages of dissimilar partners (methods of one domain with alien
particulars of another) are often among the most fruitful of intellectual unions.
This understanding of Lyell's ingenious method for dating the Tertiary also
permits us to grasp the rationale and organization behind the last two
volumes of the Principles of Geology, for both are centered upon Lyell's
attempt to apply time's cycle as a working method of history. We may view
volume II, with some simplification, as a long defense of "species as
particles" in a world of time's stately cycle-setting up, if you will, the
metaphor of the beanbag. With this key, we understand Lyell's true design
and do not misread