Word of the marvel reached the Medici palace in Florence. The
Grand Duke Ferdinand II, an aficionado of natural history, ordered
that the shark be brought at once so that his court scientists
could examine it. But it was too huge, and its flesh had already
begun to putrefy. The fishermen hacked off the head and threw
the rest of the corpse into the sea. The head was loaded onto
a cart to be sent up the valley of the Arno to Florence.
The year was 1666. Florence, indeed all of Europe, was in a state
of transition. The Renaissance had pretty much run its course.
The Protestant Reformation was a done deal. The Age of Enlightenment,
on the other hand, was barely on the horizon. It was an awkward,
in-between age reborn, reformed, but not yet enlightened.
A generation earlier, the Pope had forced Galileo Galilei to
renounce his belief in the Copernican theory of the solar system.
Galileo had based his opinions on his own observations of the
sky, rather than on the Church-approved texts: Aristotle and the
Bible. And though he accepted his punishment, he held firm to
his convictions about science. True scientific knowledge came
from experiments and direct observation of nature, he believed,
not from books, even sacred ones. He lived out his final years
in Florence, protected by the Grand Duke. Now Ferdinands
court was home to a scientific academy founded by several of Galileos
former pupils determined to keep his spirit alive.
Newest to the group was a diminutive, soft-spoken anatomist from
Denmark named Nicolaus Steno. Only 28 years old, he was already
famous for his acute powers of observation and his preternatural
skill with a scalpel. His discoveries had created sensations in
Amsterdam and in Paris, the twin intellectual capitals of Europe.
His bold challenges to conventional theories about the heart and
the brain had inevitably made him enemies, but also won him many
admirers. The Florentine scientists welcomed him as one of their
own. When the monstrous shark head arrived in Florence and was
brought into the anatomical theater to be dissected, it naturally
fell upon Steno to do the honors.
The chance capture of a shark and its dissection by a young scientist
eager to prove himself before a prestigious Italian court marked
the unlikely beginning to an intellectual revolution that, in
its way, was as profound as that of Galileo and Copernicus. Their
revolution had shifted the human position in space: It dislodged
us as the fixed center of the cosmos and set our world in motion.
Stenos changed our place in time. It removed us from the
center of the standard Biblical narrative and gave our world a
new history. The time encompassed by this new history expanded
from a mere six thousand years to nearly five billion. Vastly
older than the human species, the world could no longer be claimed
as our exclusive domain.
Steno discovered that the crust of the earth contained an archive
of its most ancient history. Up until that time, scholars had
relied only on the written word the Bible and the texts
of the Ancients to delve into the past. To the new philosophers
of the burgeoning Scientific Revolution, the past had been irrelevant:
They were interested in natures timeless laws, not its historical
development. Because no one had ever tried to read the chronicle
recorded in the Earths geologic strata, no one grasped the
stupendous changes the world had undergone over its staggeringly
long past. But without this perspective, nothing about the forces
that shape our physical world earthquakes, volcanoes, erosion,
climate could ever make scientific sense. The static, mechanical
concept of the world had to be replaced by a dynamic, evolutionary
This revolution in our understanding of the Earth, triggered
by Steno, gathered momentum slowly. Not until the end of the eighteenth
century was it in full swing; not until the middle of the twentieth
century was it complete. It was resisted as bitterly by scientists
as by theologians. It was embraced more readily by Romantic poets
than by Enlightenment philosophers. Ironically, the man who launched
it never publicly challenged the six-thousand-year Biblical timescale
that his science eventually overturned. Yet even in his final
years, which he devoted entirely to religion, he never renounced
his science either.
The story of Steno is full of such ironiesand of pathos,
as well. The genius of his ideas was never fully appreciated during
his lifetime. He died young, at 48. At one time a scientist and
darling of one of Europes most lavish courts, he became
at the end of his life an ascetic priest. His poverty and fasting,
said one friend, had reduced him to "a living corpse."
But that day in Florence he was still at the height of his scientific
powers. He had a medical education that, typically for the times,
had covered everything from anatomy to astrology. He had the support
of a wealthy sovereign. And, most important, he had a mind given
to taking unexpected leaps. From the shark, it leaped to a seemingly
unrelated question, one that, old as it was, could still generate
heated debate. It was not only his answer to this question, but
the way he sought to prove it, that triggered the scientific exploration
of the worlds distant past.
The question was this: Why are seashells often found far from
the sea, sometimes embedded in solid rock at the tops of mountains?
The ancient Greeks had known and written about these seashells.
Medieval theologians had noticed them in the building stones of
their cathedrals. Miners and quarrymen found them, as did farmers,
shepherds, and travelers. Even the Pope in Rome must have noticed
them and wondered, because they littered the slopes of Vatican
Today we think it natural to say that the seashells were left
by a sea that once covered the land. This, in fact, was the explanation
offered by the ancient Greeks. The very earliest of the Greek
philosophers, the so-called Pre-Socratics, made it the keystone
of their various theories of the world, six centuries before Christ.
Aristotle continued the tradition, writing that the waxing and
waning of the seas were part of the worlds "vital process."
The land naturally experienced many inundations over the course
Yet most educated people of Stenos time rejected this idea.
They thought instead that the shells grew within the Earth. Despite
all appearances, the seashells were not actually seashells at
all. No clams had ever lived inside the fossil clam shells; no
seas had ever covered the mountains.
Bizarre as it may seem today, this idea made perfect sense to
the seventeenth-century mind. Some of the more mystical currents
of Renaissance thought were still popular, even among those who
prided themselves for their rationality. Neo-Platonists and Hermetic
philosophers had taught that all things on and within the Earth
were shaped by "plastic forces" and invisible emanations
from the stars. No one knew how these mysterious forces and emanations
actually produced stones in the shapes of seashells, but the world
was a mysterious place: No one knew how a magnets force
caused it to attract an iron bar or orient itself toward the north.
No one knew how the suns "emanations" made flowers
grow. These things happened in front of the eyes, yet they were
still mysterious. Who could say what was or was not possible in
the depths of the Earth?
The theory that fossil seashells grew right there in the rocks
also had the advantage of sidestepping some thorny problems faced
by other explanations. There was, for example, a long tradition
among Christian writers that fossil seashells were relics of Noahs
flood. The shells were tangible proof of scripture and a visible
reminder of Gods power and human sinfulness. Missionaries
found them useful for demonstrating to the local pagans that the
flood described in the Bible had been universal, not something
inflicted on the Hebrews alone.
But a closer look at both scripture and fossil seashells led
to disconcerting questions. There were contradictions, some easier
to reconcile than others. The shells resembled species that lived
in salt water, but forty days and nights of rain would have made
a freshwater flood. And how could so many shellfish become spread
so widely in a flood that, according to the Bible, lasted no more
than a year? Medieval monks had felt free to fudge a little in
their reading of the text. Maybe it was the overflowing sea that
caused the flood, not rain, as was written. Maybe it had lasted
somewhat longer than the text said. It was a respectable practice.
Saint Augustine and the other early church fathers had not hesitated
to interpret scripture metaphorically when necessary.
There was another, stickier, problem, though, one that metaphors
couldnt easily solve. The Bible said God created the solid
Earth and gave it its form in the very first week. Noahs
flood happened much later. How, then, how did seashells get inside
rocks, which had supposedly already been created when the
flood took place? The flood might have left shells on mountains,
but not in them.
Of course, it was possible to call them a miracle, and leave
it at that, but the budding scientific minds of the seventeenth
century were reluctant to do this. They wanted to explain the
world by natural law whenever possible. And since the Reformation,
metaphorical interpretations of Scripture had become increasingly
frowned upon, too. Luther and Calvin had put the Bible at the
center of their faith; the plain meaning of its words were not
to be trifled with.
Even the "vital processes" suggested by Aristotle offered
no way out of the dilemma. It may have been a perfectly acceptable
explanation for low-lying shell deposits near the coasts, but
for the shells in the mountains, it could lead to dangerous ideas.
Aristotle had emphasized the slowness of geographical changes.
In the time it would take for an ocean to dry up, or a mountain
to sink beneath the waves, whole nations might arise and perish.
He imagined an eternal worldas many pagans of his time didwhich
put no limits at all on time, and he claimed that these natural
inundations occurred again and again over the ages. For the modern
seventeenth-century man, this simply could not be true. There
was not enough time. Nothing of the sort had ever been seen in
all the centuries of recorded history. Mount Sinai still stood
as high as it had when Moses brought down the Ten Commandments.
The Mediterranean Sea had not dried up appreciably, either. How,
then, could geography have been overhauled many times when the
world itself was known to be less than six thousand years old?
The evidence for this time limit came from the Bible, which was
supposed to contain a complete history of the world. By tallying
all the generations and reigns of kings recorded in its pages
one could estimate the total time elapsed since Creation. The
answers varied, depending on which version of scripture that one
used, but none exceeded six thousand years. The most definitive
and precise was the one calculated by James Ussher, the Anglican
Archbishop of Armagh, Ireland.
Ussher was one of the most formidable scholars of his time; it
was said that his personal library was the largest in all of western
Europe. He devoted his life to compiling his chronology. The date
he gave for Creation was Sunday, October 23, 4004 B.C. When he
died in 1656, a year after his book was published, the world would
have been 5,660 years old, by his reckoning. And he believed,
as did many others, that the world was not likely to get much
older. Six thousand years would be the limit for the worlds
total life span.
This was also revealed in the Bible, whose words were assumed
to be not only history, but prophesy. The six days of Creation
in Genesis foretold that the world would exist for six
ages. How long was an "age"? The Bible revealed this,
too. "In Thy sight, O Lord," it read, " a thousand
years are as one day." Six thousand years, then, was all
the time there would ever be.
For a Christian, the world could not be eternal because only
God was eternal. To say that the world was eternal denied that
it had a beginning, that it had been created by God, indeed that
it had been created at all. People were eternal, too, in the cyclical
view of time. This raised all kinds of problems. If a person could
borrow money in one cycle, and repay it in the next, which some
pagans saw as a perfectly acceptable practice, then where was
the urgency for a sinner to reform and repay his debt to God?
And the whole idea of salvation was thrown into question if the
birth, crucifixion, and resurrection of Christ were not unique
events in time, but happened again and again ad infinitum.
"God forbid that we should believe this," wrote Saint
Augustine, "For Christ died once for our sins, and rising
again, dies no more."
The Bible plainly said that the world was created, not eternal.
Genesis gave the story of how it happened. Some people,
including Saint Augustine, allowed that the six days of Creation
were probably metaphorical although Saint Augustine thought
that six days were too long for an Almighty God who could
create a universe in an instant if he wanted to. But even if one
was willing to add a little slack to the Creation week, the history
of the world still had to be finite. Time went in one direction,
it did not loop around, it had a beginning and an end.
Given the difficulty of explaining fossil seashells in a six
thousand-year-old world, and the repugnance of the only apparent
alternative, Aristotles eternal world, the idea that the
fossils grew in place was understandably attractive. The flood
still had its advocates Martin Luther notably among them
and a few daring souls even dared to openly support the
eternalist solution. But to argue that the seashells actually
were seashells was to swim against some strong religious and scientific
This, of course, is what Steno would do. And, along the way,
he would offer his ideas on the growth of crystals, the erosion
of land, the growth of mountains, and, most famously, the laying
down of sedimentary strata. What gelled in his anatomists
mind was a scientific approach to the anatomy of the Earth, how
its parts grew and how their development could be understood.
It was, in effect, a new science, sprung almost fully formed from
the mind of one man.
There was no science of the Earths history at the time,
because the Earth was not really considered to even have
a history. People had a history; not things, not nature. For the
orthodox Christian, each part of the world had been created in
an instant, more or less in its present form. There was no point
in asking how mountains or valleys formed. They had just been
created. No further explanation was necessary or even possible.
If someone allowed that there had, in fact, been a few changes
since Creation, these were seen as inherently chaotic. Changes
could only mean the decay of Gods originally perfect Creationchanges
for the worse, by definitionand so not worthy of Christian
contemplation. And, finally, all important events in the six thousand
years since the beginning of the world were recorded in the Bible,
anyway. There was no need for any further investigation.
Unlike his contemporaries, however, Steno found not chaos but
order in the crust of the Earth. It wasnt the perfectly
regular order that astronomers found in the heavens, or the mathematical
order that physicists found in pendulums and projectiles. It was
the order of a well-told story, a narrative in which one part
follows another with inevitable logic, but the conclusion is not
predictable. He found the logic by which the faulting, uplift,
erosion, and stratification of a landscape and the bedrock beneath
it could be put into an intelligible sequence. From the narrative
he read in the rocks, he could write a history of the landscape.
And the logic, if extended, could reveal the history of the entire
The backbone of his system was a simple but tremendously powerful
idea. Recognizing that the layers of rock that entombed fossil
shells were made by the gradual accumulation of sediment, he realized
that each layer embodied a span of time in the past. He saw no
way to measure the number of years or centuries involved, and
was loathe to speculate, but it was clear that the layers, one
on top of the other, formed an unambiguous sequence: The lowest
layer had been formed first, the highest last. Depending on their
fossils and their sediments, the layers recorded the succession
of seas, rivers, lakes, and soils that once covered the land.
Geologists call Stenos insight the "Principle of Superposition."
It means that, layer by layer, the history of the world is written
Just as Galileos telescope had opened up space to science,
Stenos strata opened up the past. In an astonishing feat
of intellectual focus, Steno produced his seminal geological work
in a period of less than two years; two years in which his personal
life also underwent major upheavals. Equally remarkable, his new
science is outlined in barely 100 pages of text and just a handful
of diagrams. His 78-page masterpiece De Solido (On Solids),
was originally intended as an abstract, a "prodromus,"
of a longer and more detailed dissertation. But that work never
materialized. De Solido was his last published geological
work. A few years later he entered the priesthood and gave up
scientific research altogether. While in Italy he had made a controversial
switch from Lutheran to Catholic, and with the zeal of a new convert
he devoted the remainder of his life to the Church.
Stenos singular approach to science made him something
of an enigma to his contemporaries. His abrupt retreat from it
has made him an enigma to many who have studied him since. He
had a mind that was extraordinarily fertile, but extraordinarily
restless. And just as he overturned many assumptions about science,
history, and faith cherished in his own time, his story overturns
many that are equally cherished in ours.