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Natural History
April, 1999

Lyell's Pillars of Wisdom.(Charles Lyell)(includes from the works of Lyell, Pliny the Younger, Pliny the Elder, and Robert Frost)

Author/s: Stephen Jay Gould

Three ancient Roman columns near Naples became the benchmarks of a new geology.

Part One:

Damping The Fires Of Vesuvius

The two classical scenarios for a catastrophic end to all things--destruction by heat and flames or by cold and darkness--offer little fodder for extended discussion about preferences, a point embedded, with all the beauty of brevity, in Robert Frost's poem "Fire and Ice," written in 1923:

   Some say the world will end in fire,
   Some say in ice.
   From what I've tasted of desire
   I hold with those who favor fire.
   But if it had to perish twice,
   I think I know enough of hate
   To say that for destruction ice
   Is also great
   And would suffice.

Among the natural phenomena that poets and scholars have regarded as heralds or harbingers of the final consummation, volcanic eruptions hold pride of place. Mount Vesuvius may represent a mere pimple of activity compared with the Indonesian explosions of Tambora in 1815 or Krakatau in 1883, but a prime location on the Bay of Naples, combined with numerous eruptions at interesting times, has promoted this relatively small volcano into a primary symbol of natural terror. Given our traditional dichotomy for unpleasant finalities, I note with some amusement that the two most famous encounters of celebrated scientists with this archetypal volcano--one in each millennium of modern history--have elicited contrasting comparisons of Vesuvian eruptions with the end of time: "lights out" for the first, "up in flames" for the second.

Pliny the Elder (23-79 A.D.) wrote a massive compendium entitled Natural History, divided into thirty-seven libri (books) treating all aspects, both factual and folkloric, of subjects now gathered under the rubric of science. Pliny's encyclopedia exerted enormous influence upon the history of Western thought, particularly during the Renaissance (literally "rebirth"), when rediscovery of classical knowledge became the primary goal of scholarship. Several editions of Pliny's great work appeared during the first few decades of printing, following the publication of Gutenberg's Bible in 1455.

In August of 79 A.D., while serving as commander of the Roman fleet in the Bay of Naples, Pliny noted a great cloud arising from Mount Vesuvius. Following the unbeatable combination of a scientist's curiosity and a commander's duty, Pliny sailed toward the volcano, both to observe more closely and to render aid. He went ashore at a friend's villa, made a fateful decision to abandon the shaking houses for the open fields, and died by asphyxiation in the same eruption that buried the cities of Pompeii and Herculaneum.

Pliny the Younger (61-113 A.D.), his nephew and adopted son, remained at their villa a few miles west of the volcano to continue (as he stated) his studies of Livy's historical texts. After the dust had settled (sorry, but I couldn't resist this opportunity to use a cliche literally), he wrote two famous letters to the historian Tacitus, describing what he had heard of his uncle's fate and what he had experienced as his own. Pliny the Younger recounted all the horrors of shaking houses, falling rocks, and noxious fumes, but he emphasized the intense darkness produced by the spreading volcanic cloud, a pall that he could compare with only one scenario for the end of time (see endnote, page 88):

   A darkness overspread us, not like that of a cloudy night, or when there is
   no moon, but of a room when it is shut up and all the lights are
   extinguished. Nothing then was to be heard but the shrieks of women, the
   screams of children, and the cries of men ... some wishing to die from the
   very  fear of dying, some lifting up their hands to the gods; but the
   greater part imagining that the last and eternal night had come, which was
   to destroy both the gods and the world together.

Athanasius Kircher (1601-1680), a German Jesuit who lived in Rome, where he served as an unofficial "chief scientist" for the Vatican, cannot be regarded as a household name today (although he served as a primary character and inspiration for Umberto Eco's latest novel, The Island of the Day Before). Nonetheless, Kircher ranked among the most formidable intellects of the seventeenth century. He wrote, for example, the most famous works of his time on magnetism, music, Chinese culture (the Jesuit order had already established a major presence in China), and the interpretation of Egyptian hieroglyphics (his system ultimately failed, but did offer important clues and inspiration for later scholars). Kircher tumbled into intellectual limbo largely because his Neoplatonic worldview fell victim to the alternative concept of causality that we call modern science--a reform that Galileo (whom Kircher had more or less replaced as a leading scientist, in the eyes of the Vatican) had espoused in the generation just before and that Newton would carry to triumph in the generation to follow.

In 1664 Kircher published his masterpiece, an immense and amazing work entitled Mundus subterraneus (The Underground World) and covering all aspects of anything that dwelled or occurred within the earth's interior--from lizards in caves, to fossils in rocks, to mountain springs, earthquakes, and volcanoes. Kircher had been inspired to write this work in 1637-38 when he witnessed the major eruptions of Etna and Stromboli. In 1631, after centuries of quiescence, Mount Vesuvius had also erupted, and Kircher eagerly awaited the opportunity to visit this most famous volcano on his return voyage to Rome.

He climbed the mountain at night, guided by flames still issuing from the active crater, and then lowered himself as far as he dared into the fuming, bubbling vent the next morning. When he published his great treatise twenty-five years later, the memory of his fear and wonder remained so strong that he prefaced his entire volume with a vivid personal tale of his encounter with a primary symbol for the end of time. But Kircher favored Robert Frost's alternative scenario off ire:

   In the middle of the night, I climbed the mountain with great difficulty,
   moving upward along steep and rugged paths, toward the crater, which,
   horrible to say, I saw before me, lit entirely by fire and flowing pitch,
   and enveloped by noxious fumes of sulphur ... Oh, the immensity of divine
   power and God's wisdom! How incomprehensible are thy ways! If, in thy
   power, such fearful portents of nature now punish the duplicity and
   maliciousness of men, how shall it be on that last day when the earth,
   subjected to thy divine anger, is dissolved by heat into its elements.
   (Author's translation from Kircher's Latin)

I like to imagine that as he wrote these lines, this greatest of priestly scientists was humming, sotto voce, the haunting Gregorian tune of the "Dies Irae," the most famous prayer about the Last Judgment:

   Dies irae, dies illa Solvet saeclum in favilla. (On this day of anger, the
   world will dissolve into ashes.)

Vesuvius looms over modern Naples even more ominously than Mount Rainier over Seattle, for Vesuvius lies much closer to the city center and sports a record of much more recent and frequent activity--although neither city could ever claim a medal from the global commission on safe geological siting. (My father, as a GI in World War II, observed the aftermath of the last eruption of Vesuvius in 1944.) In light of the historical testimony, combined with the volcano's continuing and pervasive presence for any modern visitor (from the majestic mountain standing tall on the horizon to the petrified bread and the bathroom graffiti--evidence of ordinary lives suddenly extinguished one fine day in Pompeii), how could anyone fail to draw from Vesuvius the same geological lesson that led Pliny and Kircher to extrapolate from a raging local volcano to a globally catastrophic end of time: that the history of our planet must be ruled by sudden cataclysms that rupture episodes of quiescence and mark the dawn of a new order?

And yet the most famous geological invocation of volcanism in the Bay of Naples, bolstered by the most celebrated visual image in the profession's entire history, propelled scientific views of Earth in the opposite direction--toward a theory that currently observable processes, operating at characteristically gradual rates, could explain the full pageant of planetary history without any invocation of episodic global paroxysms or early periods of tumultuous planetary change superseded by the staid global maturity of our own time.

Charles Lyell (1797-1875), the primary architect of this "uniformitarian" view and the most famous name in the history of anglophone geology, visited Naples on his "grand tour" of European cultural centers, the voyage that nearly every British gentleman undertook as an essential part of his education. He made all the customary stops, from the steaming vents and bubbling pools of the Phlegraean Fields to the excavations of Pompeii and the obligatory ascent of Vesuvius. (Following its more active eruption, the volcano continued to bubble and steam throughout the late eighteenth century, during the long tenure in Naples of British diplomat and aficionado of volcanoes Sir William Hamilton--a level of ardent activity matched only by the torrid, and rather public, affair between Hamilton's wife, Emma, and Admiral Horatio Nelson himself.)

How, then, could Lyell redefine Naples as a source of support for a theory so contrary both to traditional interpretations and to the plain meaning of the grandest local sights? When the editor of Natural History asked me to devote this month's essay to the "travel" theme of this issue--and even offered to cover some expenses for an on-site excursion--I decided to adopt this question as a focus for fulfilling the first half (while greatly delaying the second) of a familiar proverb: See Naples and die.

I wanted to observe the palpable signs of Pliny's misfortune (the excavations of Pompeii and Herculaneum) and to follow Kircher's path to their immediate source. But most of all, I wanted to visit the site of Lyell's visual epiphany--the source of the frontispiece for his Principles of Geology (1830-33), perhaps the most important scientific textbook ever written, and the primary icon for transforming the Vesuvian landscape from a poster for catastrophism into a paradoxical proof of triumphant gradualism--the three Roman columns of the so-called Temple of Serapis (actually a marketplace) at Pozzuoli, near Naples. (I shall document, in the second installment of this essay, how Lyell used these three pillars as a "tide gauge" to record extensive and gradual changes in land and sea levels during the past two thousand years--a uniformitarian antidote to the image of fiery Vesuvius as a symbol for catastrophic global endings.)

The cliches of travel literature require an arduous journey sparked with tales of adventure and danger. But I have never managed to strike up a friendship with stylistic conventions, and I remain a city boy at heart (and therefore quite unafraid of rather different kinds of dangers). In truth, I never got to the top of Vesuvius. My rented car carried no tire chains, and a sheet of January ice had closed the road. As for Pozzuoli, I can't claim any more of an adventure than a trip to South Ferry or Ozone Park: Pozzuoli is the last stop on the Neapolitan subway.

But then, why should intellectual content correlate with difficulty of physical access--a common supposition that must rank among the silliest of romantic myths? The material for some of the greatest discoveries in the history of science has stood on library shelves or resided, unsuspected for decades, in museum drawers. By all means, take that dogsled across the frozen wastes if no alternative exists, but if the A Train also goes to the same destination, why not join Duke Ellington for a smoother ride?

To reach the specifics of Pozzuoli on a literary journey, we must follow the path of Lyell's general theory. Lyell, originally a barrister by training, sought to reform the science of geology on both substantive and methodological grounds. He based his system--one might say his brief--on two fundamental propositions.

First, the doctrine of gradualism: Modern causes, operating entirely within the range of rates now observable, can explain the full spectrum of geological history. Apparently grandiose or catastrophic events really occur by a summation of small changes through the immensity of geological time--the deep canyon carved grain by grain, the high mountain raised in numerous increments of earthquake and eruption over millions of years.

Second, the claim for a nondirectional or steady-state earth: Standard geological causes (erosion, deposition, uplift, and so on) show no trend either to increase or decrease in general intensity through time. Moreover, even the physical state of the earth (relative temperatures, positions of climatic belts, percentages of land and sea) tends to remain roughly the same or to cycle around and around through time. Change never slows or ceases; mountains rise and erode; seas move in and out. But the average configuration of the earth experiences no systematic trend in any sustained direction. Lyell even believed at first--although he changed his mind by the 1850s, when he finally concluded that mammals would not be found in the oldest strata--that the average complexity of life had remained constant. Old species die, and new species originate (by creation or by some unknown natural mechanism). But clams remain clams, and mammals, mammals--from the earliest history of life until now.

When a scientist proposes such a comprehensive system, we often gain our best insights into the sources and rationale for his reforms by explicating the alternative worldview of his opponents. New theories rarely enter a previous conceptual void; rather, they arise as putative improvements or replacements for previous conventionalities. In this case, Lyell's perceived adversaries advocated an approach to geology often called either catastrophism or directionalism (in opposition to Lyell's two chief tenets of gradualistic change on an earth in steady-state).

Catastrophists argued that most geological change occurred in rare episodes of truly global paroxysm, marked by the "usual suspects" of volcanism, mountain building, earthquakes, and flooding. Most catastrophists also held that the frequency and intensity of such episodes had markedly decreased through time, thus contrasting a feisty planetary youth with a much calmer present.

For most catastrophists, these two essential postulates flowed logically from a single theory about Earth's history--the origin of the planet as a molten fireball spun off from the Sun (according to the hypothesis, then favored, of Kant and Laplace), followed by progressive cooling. As this cooling proceeded, the outer crust solidified while the molten interior contracted continuously. The resulting instability--caused, almost literally, by an enlarging gap between the solidified crust and the contracting molten interior--eventually induced a sudden global readjustment as the crust fractured and collapsed upon the contracted molten core. Thus, directionalism based on continuous cooling linked the catastrophism of occasional readjustment by crustal collapse with the hypothesis of a pervasive "arrow of time" leading from a fiery beginning, replete with more frequent and more intense paroxysms, to our current era of relative calm and rarer disruption.

Incidentally, this account of catastrophism as a genuine and interesting scientific alternative to Lyellian uniformity disproves the conventional canard, originally floated as a rhetorical device by Lyell and his partisans but then incorporated uncritically as the conventional wisdom of the profession. In this Manichaean account, catastrophism represented the last stronghold for the enemies of modern science: the struggle of theologically tainted dogmatists to preserve both the literal time scale of Genesis and the miraculous hand of God as history's prime mover by invoking the doctrine of global paroxysm to compress the grand panoply of geological change into a mere few thousand years. In fact, by the 1830s all scientists--catastrophists and uniformitarians alike---had accepted the immensity of geological time as a central and proven fact of their emerging profession. Catastrophists upheld a different theory of change on an equally ancient Earth, and their views were no less "scientific"--and no more theologically inspired or influenced--than anything touted by Lyell and his school.

The personal, social, and scientific reasons behind Lyell's commitments represent a complex and fascinating subject well beyond the scope of this essay. But we may note the overt strategy, chosen by this master of persuasive rhetoric, this barrister manque, to promulgate his uniformitarian doctrine as the centerpiece of his textbook, Principles of Geology. In part, he chose the substantive route of arguing that the world, as revealed by geological evidence, just happens to operate by gradual and nondirectional change. But Lyell awarded primacy of place to a methodological claim: only such a uniformitarian approach, he urged, could free the emerging science of geology from its previous fetters of fanciful, and largely armchair, speculation.

If global paroxysms forge most of history, Lyell argued, then how can we ever develop a workable science of geology--for we have not witnessed such events in the admittedly bruited duration of human history, and we therefore have no observational basis for empirical study? And if a tumultuous past operated so differently from a calmer present, then how can we use modern processes--the only mechanisms subject to direct observation and experiment, after all--to resolve the past? But on an Earth in steady-state, built entirely by modern causes acting at current intensities, the present becomes, in an old pedagogical cliche, "the key to the past," and Earth's entire history opens to scientific study. Thus, in a famous statement of advocacy, Lyell condemns catastrophism as a doctrine of despair, while labeling his uniformitarian reform as the path to scientific salvation:

   Never was there a dogma more calculated to foster indolence, and to blunt
   the keen edge of curiosity, than this assumption of the discordance between
   the former and the existing causes of change. It produced a state of mind
   unfavourable in the highest conceivable degree to the candid reception of
   the evidence of those minute, but incessant mutations, which every part of
   the earth's surface is undergoing.... The student, instead of being
   encouraged with the hope of interpreting the enigmas presented to him in
   the earth's structure--instead of being prompted to undertake laborious
   inquiries into ... causes now in operation, was taught to despond from the
   first. Geology, it was affirmed, could never rise to the rank of an exact
   science--the greater number of phenomena must forever remain

      In our attempt to unravel these difficult questions, we shall adopt a
   different course, restricting ourselves to the known or possible operations
   of existing causes.... We shall adhere to this plan ... because ... history
   informs us that this method has always put geologists on the road that
   leads to truth--suggesting views which, although imperfect at first, have
   been found capable of improvement, until at last adopted by universal
   consent. (Principles of Geology, vol. 3, chap. 1, 1833)

Large intellectual struggles cannot be won by success in easy and simple skirmishes. Adversaries must also be outflanked on their home ground, where superior knowledge and forces should have rendered them invincible. A new theory must meet and encompass the hardest and most apparently contradictory cases head on. Lyell understood this principle and recognized that he would have to bring the Vesuvius of Pliny and Kircher, of Pompeii and Emma Hamilton's fire, into his uniformitarian camp--not as a prisoner but as a proud example. No other place or subject receives even half so much attention throughout the three volumes of the Principles of Geology.

Lyell centered his uniformitarian case for Naples and Vesuvius on two procedural themes that embodied all his logical and literary brilliance as geology's greatest master of argument. He first invoked the cardinal geological principle of appropriate scale by pointing out that a Vesuvian eruption, while ultimately catastrophic for the baker or blacksmith of Pompeii, not only causes no planetary disruption at its own moment of maximal intensity, but then falls even further into insignificance when several hundred years of subsequent quiescence erase its memory from the populace and erode its products from the landscape.

Why, then, should such a local catastrophe serve as an unquestioned model for extrapolation to sudden global doom? Perhaps we should draw an opposite lesson from the same event: local means local--and just as the canyon deepens grain by grain, so does the mountain chain rise gradually, eruption by eruption, over extended time. At most, Vesuvius teaches us that the increments of gradualism can be large at human scale--the lava field versus the eroded sand grain--while still small by global standards. In 1830, at the end of a long chapter entitled "History of the volcanic eruptions in the district around Naples" Lyell wrote:

   The vast scale and violence of the volcanic operations in Campania [the
   region of Italy surrounding Naples] in the olden time, has been a theme of
   declamation.... Instead of inferring from analogy that ... each cone rose
   in succession--and that many years and often centuries of repose intervened
   between each eruption--geologists seem to have conjectured that the whole
   group sprung up from the ground at once, like the soldiers of Cadmus when
   he sowed the dragon teeth.

Moreover--continued Lyell, in closing the first volume of his tenth edition (1867)--even by purely local standards, natural catastrophes usually impose only a fleeting influence upon history. Most inhabitants, he argued, view Campania as a land of salubrious tranquility. As for Vesuvius itself, even the worst natural convulsion cannot match the destructive power of human violence and venality. In a striking literary passage, Lyell reminds us that Vesuvius posed its greatest danger to the Roman empire as an abode for the armies of Spartacus' slave revolt in 73 B.C. rather than as a source of lava and poisonous gases in 79 A.D.:

   Yet what was the real condition of Campania during those years of dire
   convulsion? "A climate," says Forsyth, "where heaven's breath smells sweet
   and wooingly--a vigorous and luxuriant nature unparalleled in its
   productions--a coast which was once the fairy-land of poets, and the
   favorite retreat of great men." ... The inhabitants, indeed, have enjoyed
   no immunity from the calamities which are the lot of mankind; but the
   principal evils which they have suffered must be attributed to moral, not
   to physical, causes--to disastrous events over which man might have
   exercised a control, rather than to inevitable catastrophes which result
   from subterranean agency. When Spartacus encamped his army often thousand
   gladiators in the old extinct crater of Vesuvius, the volcano was more
   justly a subject of terror to Campania than it has ever been since the
   rekindling of its fires.

For his second theme, Lyell emphasized the importance of interpreting evidence critically but not necessarily literally. The geological record, like most archives of human history, features more gaps than documents. (In a famous metaphor, later borrowed by Darwin for a crucial argument in the Origin of Species, Lyell compared the geological record to a book with very few pages preserved; of these pages, few lines; of the lines, few words; and of the words, few letters.) Moreover, the sources of imperfection often operate in a treacherous way, because they do not delete data at random but rather in a strongly biased fashion--thus tempting us to regard some causes as dominant merely because the evidence of their action tends to be preserved, while signs of more truly important factors may differentially disappear from the record.

Lyell recognized that catastrophes usually leave their signature, for extensive outpourings of lava or widespread fracturing of strata by earthquakes resist erasure from the geological record. But the publishers of time often print equally important evidence for gradual change---the few inches of sediment that may accumulate during millions of years in clear calm seas or the steady erosion of a riverbed grain by grain--upon missing pages of the geological book. This bias not only overemphasizes the role of catastrophes in general but may also plant the false impression that intensity of geological change has diminished through time--for if the past preserves only its catastrophes, while the present yields more balanced data for all modes of change, then a literal and uncritical reading of geological evidence may lead us to erroneous inferences about a more tumultuous past.

Lyell summarizes this crucial argument about biases of preservation in a brilliant metaphor for Mount Vesuvius. "Suppose," he writes, "we had discovered two buried cities at the foot of Vesuvius, immediately superimposed upon each other, with a great mass of tuff and lava intervening, just as Portici and Resina, if now covered with ashes, would overlie Herculaneum." (When Lyell visited the area in 1828, excavations at Herculaneum had proceeded further than those at Pompeii: hence Lyell's primary citation of a town that now ranks second to Pompeii in terms of memorializing the destructive powers of Vesuvian eruptions.) If we read such a sequence literally, we would have to conclude that sudden and catastrophic changes forged history. The remains of an Italian city, littered with the modern debris of beer cans and bicycles, would overlie the strata of a Roman town, replete with fragments of amphoras and chariots--with only a layer of volcanic rock between. We would then infer that a violent catastrophe had triggered a sudden mutation from Latin to Italian and from chariot wheels to automobile tires (for we would note the genuine relationships while missing all the intermediary stages)--simply because the evidence for nearly two thousand years of gradual transitions failed to enter a historical record strongly biased toward the preservation of catastrophic events.

A successful campaign for substantial intellectual reform also requires a new and positive symbol or icon, not just a set of arguments (as presented so far) to refute previous interpretations. Vesuvius in flames, the icon of Pliny and Kircher, must be given a counterweight--some Neapolitan image, also a consequence of Vesuvian volcanism, to illustrate the efficacy of modern causes and the extensive results produced by accumulating a series of small and gradual changes through substantial time. Lyell therefore chose the Roman pillars of Pozzuoli--an image that he used as the frontispiece for all editions of the Principles of Geology (and also as an embossed golden figure on the front cover of later editions). As the introductory image in the most famous geological book ever written, the pillars of Pozzuoli became icon numero uno for the earth sciences. I cannot remember ever encountering a modern textbook that does not discuss Lyell's interpretation of these three columns, invariably accompanied by a reproduction of Lyell's original figure or by an author's snapshot from his own pilgrimage. Next month, in the closing installment of this essay, I shall analyze Lyell's account of the Pozzuoli pillars as an example of both the virtues and the dangers of trying to encompass all nature within the architecture of one brilliant conceptual scheme.

NOTE: In one of those odd coincidences that make essay writing, and intellectual life in general, such a joy, I happened to be reading, just two days after completing this essay, a volume of Francis Bacon's complete works. I knew the old story about his death in 1626. Bacon, who loved to perform and report simple experiments of almost random import (his last and posthumous work, Sylva Sylvarum [The Forest of Forests], lists exactly one thousand such observations and anecdotes), wanted to learn if snow could retard putrefaction. He therefore stopped his carriage on a cold winter day, bought a hen from a poultryman, and stuffed it with snow. He was then overtaken with a sudden chill that led to bronchitis. Bacon was too ill to reach London, so he sought refuge instead at the home of a friend, the Earl of Arundel, where he died a few days later.

But I had never read Bacon's last and poignant letter (written to his host), with its touching reference to Pliny the Elder's similar demise in his boots. I was struck, in the context of this essay, by another resemblance between the two deaths--their common occurrence at one end of the spectrum of fire and ice:

   My very good Lord,

      I was likely to have had the fortune of Caius Plinius the elder, who
   lost his life by trying an experiment about the burning of the mountain
   Vesuvius: for I was also desirous to try an experiment or two, touching on
   the conversion and induration of bodies. As for the experiment itself, it
   succeeded excellently well; but in the journey (between London and
   Highgate) I was taken up with such a fit of casting [an old term for
   vomiting, from casting in the sense of throwing out or up, as in dice or a
   fishing line] as I know not whether it were the stone, or some surfeit
   [that is, kidney or gallstones, or overeating], or cold, or indeed a touch
   of them all three. But when I came to your lordship's house, I was not able
   to go back, and therefore was forced to take up my lodging here.... I kiss
   your noble hands for the welcome .... I know how unfit it is for me to
   write to your lordship with My other hand than my own, but by my troth my
   fingers are so disjointed with this fit of sickness, that I cannot steadily
   hold a pen.

Stephen Jay Gould teaches biology, geology, and the history of science at Harvard University. He is also the Frederick P. Rose Honorary Curator in Invertebrates at the American Museum of Natural History.

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