icon. But I also remembered Darwin's first choice for an organic metaphor or
picture of branching to capture his developing views about descent with
modification and the causes of life's diversity—the "coral of life" of his "B Note-
book" on transmutation, kept during the 1830's as he became an evolutionist and
struggled towards the theory of natural selection (see Barrett et al., 1987).
As I began to write this summary chapter, I therefore aimlessly searched
through images of Cnidaria from my collection of antiquarian books in
paleontology. I claim no general significance whatsoever for my good fortune, but
after a lifetime of failure in similar quirky quests, I was simply stunned to find a
preexisting image—not altered one iota from its original form, I promise you, to
suit my metaphorical purposes—that so stunningly embodied my needs, not only
for a general form (an easy task), but down to the smallest details of placement and
potential excision of branches (the feature that I had no right or expectation to
discover and then to exapt from so different an original intent).
The following figure comes from the 1747 Latin version of one of the seminal
works in the history of paleontology—the 1670 Italian treatise of the Sicilian
savant and painter Agostino Scilla, ha vana speculazione disingan-nata dal senso
("Vain speculation undeceived by the senses"— Scilla's defense, at the outset of
"the scientific revolution" of Newton's generation, for empirical methods in the
study of nature, and specifically, in this treatise, for a scientific paleontology and
the need to recognize fossils as remains of ancient organisms, not as independent
products of the mineral kingdom). This work, famous not only for an incisive text,
but also for its beautiful plates (see Fig. 1-3), engraved by an author known
primarily as an artist of substantial eminence, includes this figure, labeled
Coralium articulatum quod copio-sissimum in rupibus et collibus Messanae
reperitur ("Articulated coral, found in great abundance in the cliffs and hills of
Messina").
This model, and its organic features, work uncommonly well as a metaphor
for the Goldilockean position of definition by a barest minimum of truly
fundamental postulates. For Scilla's coral, with its branching structure (see Fig. 1-
4)—particularly as expressed in the lessening consequences of excising branches at
ever higher levels nearer the top (the analogs of disconfirming theoretical features
of ever more specialized and less fundamental import)— so beautifully captures
the nature and operation of the intellectual structure that I defended above for
specifying the essences of theories. The uncanny appropriateness of Scilla's coral
lies in the fortuity that this particular specimen (accurately drawn from nature by
Scilla, I assume, and not altered to assert any general point) just happens to include
exactly the same number of branches (three) as my Darwinian essential structure.
(They terminate at the same upper level, so I could even turn the specimen over
into a tolerably unwobbly tripod!) Moreover, since this particular genus of corals
grows in discrete segments, the joining points correspond ideally with my
metaphor of chopping planes for excising parts of structures at various levels of
importance in an intellectual entity. But, most incredibly, the segmental junctions
of
Defining and Revising the Structure of Evolutionary Theory 17