The Lying Stones of Marrakech (16 page)

No other person could possibly have provided better fuel for such a transformation in the history of human thought: this man of such restless energy; this man who operated forges and who developed the experimental and mathematical skill to infer the age of the earth from balls of iron; who composed thirty-six volumes of the greatest treatise ever written in natural history by working fourteen hours a day for more than forty years. And if all these skills and attributes could not turn the tide, Buffon also wrote in an elegant prose that placed him, a “mere” student of nature, among the leading men of letters in his interesting time. Buffon surely knew how to prevail—for style, after all, is the man himself.

2
I wrote this essay in the summer of 1998,
in medio Monicae anni
, just before a presidential impeachment.

I. W
RITING IN THE
M
ARGINS

I
ONCE HAD A TEACHER WITH AN IDIOSYNCRATIC HABIT
that distressed me forty years ago, but now—and finally, oh sweet revenge!—can work for me to symbolize the general process of human creativity. I never knew a stingier woman, and though she taught history in a junior high school in New York City, she might well have been the frugal New England farmer with a box marked “pieces of string not worth saving.” Readers who attended New York public schools in the early 1950s will remember those small yellow slips of paper, three by six inches at most, that served all purposes from spot quizzes to “canvasses” for art class. Well, Mrs. Z. would give us one sheet—only one—for any classroom exam, no matter how elaborate the required answers. She would always reply to any plea for advice about containment or, God forbid, for an additional yellow sheet (comparable in her system of values to Oliver Twist's request for more soup) with a firm refusal followed
by a cheery instruction expressed in her oddly lilting voice: “… and if you run out of room, just write in the margins!”

Margins play an interesting role in the history of scholarship, primarily for their schizophrenic housing of the two most contradictory forms of intellectual activity. Secondary commentaries upon printed texts (often followed by several layers of commentaries upon the commentaries) received their official designation as “marginalia” to note their necessary position at the edges. The usual status of such discourse as derivative and trivial, stating more and more about less and less at each iteration, leads to the dictionary definition of marginalia as “nonessential items”
(Webster's Third New International)
and inevitably recalls the famous, and literally biting, satire of Jonathan Swift:

So, naturalists observe, a flea
Hath smaller fleas that on him prey;
And these have smaller still to bite ‘em;
And so proceed
ad infinitum
Thus every poet, in his kind,
Is bit by him that comes behind
.

But margins also serve the diametrically opposite purpose of receiving the first fruits and inklings of novel insights and radical revisions. When received wisdom has hogged all the central locations, where else can creative change begin? The curmudgeon and cynic in me regards Thoreau's
Walden
as the most overquoted (and underwhelming) American classic, but I happily succumb for the first time to cite his one-liner for a vibrant existence: “I love a broad margin to my life.”

Literal margins, however, must usually be narrow—and some of the greatest insights in the history of human thought necessarily began in such ferociously cramped quarters. The famous story of Fermat's Last Theorem, no matter how familiar, cannot be resisted in this context: when the great mathematician died in 1665, his executors found the following comment in his copy of Diophantus'
Arithmetica
, next to a discussion of the claim that no natural numbers
x, y
, and
z
exist such that
x
ⁿ
+ y
ⁿ
=
z
ⁿ
, where
n
is a natural number greater than 2: “I have discovered a truly remarkable proof but this margin is too small to contain it.” Mathematicians finally proved Fermat's Last Theorem just a few years ago, to great subsequent fanfare and an outpouring of popular books. But we shall never know if Fermat truly beat the best of the latest by three hundred years, or if (as my own betting money says, admittedly with no
good evidence) he had a promising idea and never detected the disabling flaw in the midst of his excitement.

I devote this essay to the happier and opposite story of a great insight that a cramped margin did manage (just barely) to contain and nurture. This tale, for reasons that I do not fully understand, remains virtually unknown (and marginal in this frustrating sense) both to scientists and historians alike—although the protagonist ranks as one of the half dozen greatest scientists in Western history, and the subject stood at the forefront of innovation in his time. In any case, the movement of this insight from marginality in 1760 to centrality by 1810. marks the birth of modern geology, and gives us a rare and precious opportunity to eavesdrop on a preeminent thinker operating in the most exciting and instructive of all times: at a labile beginning in the codification of a major piece of natural knowledge—a unique moment featuring a landscape crossed by one hundred roads, each running in the right general direction toward a genuine truth. Each road, however, reaches a slightly different Rome, and our eventual reading of nature depends crucially upon the initial accidents and contingencies specifying the path actually taken.

In 1700, all major Western scholars believed that the earth had been created just a few thousand years ago. By 1800, nearly all scientists accepted a great antiquity of unknown duration, and a sequential history expressed in strata of the earth's crust. These strata, roughly speaking, form a vertical pile, with the oldest layers on the bottom and the youngest on top. By mapping the exposure of these layers on the earth's surface, this sequential history can be inferred. By 1820, detailed geological maps had been published for parts of England and France, and general patterns had been established for the entirety of both nations. This discovery of “deep time,” and the subsequent resolution of historical sequences by geological mapping, must be ranked among the sweetest triumphs of human understanding.

Few readers will recognize the name of Jean-Etienne Guettard (1715-1786), a leading botanist and geologist of his time, and the initiator of the first “official” attempt to produce geological maps of an entire nation. In 1746, Guettard presented a preliminary “mineralogical map” of France to the Académie Royale des Sciences. In subsequent years, he published similar maps of other regions, including parts of North America. As a result, in 1766, the secretary of state in charge of mining commissioned Guettard to conduct a geological survey and to publish maps for all of France. The projected adas would have included 230 maps, but everyone understood, I suspect, that such a task must be compared with the building of a medieval cathedral, and that no
single career or lifetime could complete the job. In 1770, Guettard published the first sixteen maps. The project then became engulfed by political intrigue and finally by a revolution that (to say the least) tended to focus attention elsewhere. Only 45 of the 230 projected maps ever saw the published light of day, and control of the survey had passed to Guettard's opponents by this time.

Guettard's productions do not qualify as geological maps in the modern sense, for he made no effort to depict strata, or to interpret them as layers deposited in a temporal sequence—the revolutionary concepts that validated deep time and established the order of history. Rather, as his major cartographic device, Guettard established symbols for distinctive mineral deposits, rock types, and fossils—and then merely placed these symbols at appropriate locations on his map. We cannot even be sure that Guettard understood the principle of superposition—the key concept that time lies revealed in a vertical layering of strata, with younger layers above (superposed upon) older beds. Guettard did develop a concept of
“bandes,”
or roughly concentric zones of similar rocks, and he probably understood that a vertical sequence of strata might be expressed as such horizontal zones on a standard geographic map. But in any case, he purposely omitted these
bandes
on his maps, arguing that he wished only to depict facts and to avoid theories.

This focus on each factual tree, combined with his studious avoidance of any theoretical forest of generality or explanation, marked Guettard's limited philosophy of science, and also (however unfairly) restricted his future reputation, for no one could associate his name with any advance in general understanding. Rhoda Rappoport, a distinguished historian of science from Vassar College and the world's expert on late-eighteenth-century French geology, writes of Guettard (within a context of general admiration, not denigration): “The talent he most conspicuously lacked was that of generalization, or seeing the implications of his own observations…. Most of his work reveals … that he tried hard to avoid thinking of the earth as having a history.”

But if Guettard lacked this kind of intellectual flair, he certainly showed optimal judgment in choosing a younger partner and collaborator for his geological mapping, for Guettard fully shared this great enterprise with Antoine-Laurent Lavoisier (1743-94), a mere fledgling of promise at the outset of their work in 1766, and the greatest chemist in human history when the guillotine literally cut his career short in 1794.

Guettard and Lavoisier took several field trips together, including a four-month journey in 1767 through eastern France and part of Switzerland. After completing their first sixteen maps in 1770, Lavoisier's interest shifted away from geology toward the sources of his enduring fame—a change made all the more
irrevocable in 1777, when control of the geological survey passed to Antoine Monnet, inspector general of mines, and Lavoisier's enemy. (Later editions of the maps ignore Lavoisier's contributions and often don't even mention his name.)

Nonetheless, Lavoisier's geological interests persisted, buttressed from time to time by transient hope that he might regain control of the survey. In 1789, with his nation on the verge of revolution, Lavoisier presented his only major geological paper—a stunning and remarkable work that inspired this essay. Amidst his new duties as
régisseur des poudres
(director of gunpowder), and leading light of the commission that invented the meter as a new standard of measurement—and despite the increasing troubles that would lead to his arrest and execution (for his former role as a farmer-general, or commissioned tax collector)—Lavoisier continued to express his intention to pursue further geological studies and to publish his old results. But the most irrevocable of all changes fractured these plans on May 8,1794, less than three months before the fall of Robespierre and the end of the Terror. The great mathematician Joseph-Louis Lagrange lamented the tragic fate of his dear friend by invoking the primary geological theme of contrasting time scales: “It took them only an instant to cut off his head, but France may not produce another like it in a century.”

All the usual contrasts apply to the team of Guettard and Lavoisier: established conservative and radical beginner; mature professional and youthful enthusiast; meticulous tabulator and brilliant theorist; a counter of trees and an architect of forests. Lavoisier realized that geological maps could depict far more than the mere location of ores and quarries. He sensed the ferment accompanying the birth of a new science, and he understood that the earth had experienced a long history potentially revealed in the rocks of his maps. In 1749, Georges Buffon, the greatest of French naturalists, had begun his monumental treatise
(Histoire naturelle
, which would eventually run to forty-four volumes) with a long discourse on the history and theory of the earth (see chapter 4).

As he groped for a way to understand this history from the evidence of his field trips, and as he struggled to join the insights published by others with his own original observations, Lavoisier recognized that the principle of superposition could yield the required key: the vertical sequence of layered strata must record both time and the order of history. But vertical sequences differed in all conceivable features from place to place—in thickness, in rock types, in order of the layers. How could one take this confusing welter and infer a coherent history for a large region? Lavoisier appreciated the wisdom of his older colleague enough to know that he must first find a way to record and compile the facts of this variation before he could hope to present any general theory to organize his data.

A geological map by Cuettard and Lavoisier, with Lavoisier's temporal sequence of strata in the right margin
.

Lavoisier therefore suggested that a drawing of the vertical sequence of sediments be included alongside the conventional maps festooned with Guettard's symbols. But where could the vertical sections be placed? In the margins, of course; for no other space existed in the completed design. Each sheet of Guettard and Lavoisier's
Atlas
therefore features a large map in the center with two marginal columns on the side: a tabular key for Guettard's symbols at the left, and Lavoisier's vertical sections on the right. If I wished to epitomize the birth of modern geology in a single phrase (admittedly oversimplified, as all such efforts must be), I would honor the passage—both conceptual and geometric—of Lavoisier's view of history, as revealed in sequences of strata, from a crowded margin to the central stage.