Don't feel bad if you've never heard of Nicolas Steno. Even though the 17th century Danish anatomist and geologist made a number of discoveries that are now seen as self-evident – namely, that the heart is a muscle that pumps blood, that tears are formed in the eye, that fossils are the remains of living organisms from previous geologic eras, and that older rocks tend to lie deeper in the earth than younger ones – his legacy, like the mysterious stones that he examined, have since been obscured by layers of historical sediment.

Perhaps some of Steno's obscurity arises from his failure to fit into a narrative that science and religion are adversaries. Unlike Galileo, whom the Catholic church famously threatened to torture if he did not recant, Steno was embraced by the Vatican. Yet his discoveries set in motion a revolution that would ultimately unseat the Bible as the authority on the age of the earth.

Steno's geological breakthrough came in 1666, when, serving as a researcher for the Grand Duke of Tuscany in Florence, he was given the opportunity to examine the head of a great white shark. The young anatomist was struck by the similarity of the shark's teeth to curious objects found embedded in rocks throughout Europe. Steno concluded that those objects actually were the teeth of ancient sharks, deposited there when the continent lay beneath the ocean.

Published in 1669, the principles in Steno's 78-page text, "On Solids," are still taught in geology classes today. Science writer Alan Cutler sums up the thesis in his 2003 biography of the scientist, "The Seashell on the Mountaintop,"

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 Steno’s insight the "Principle of Superposition." It means that, layer by layer, the history of the world is written in stone.

A decade earlier, James Ussher, an Anglican archbishop in Ireland, published his Biblical chronology of the world. By adding up the reigns of the kings and lifespans of the patriarchs and comparing them with the dates of known historical events, Ussher concluded that the world came into existence on Sunday, October 23, 4004 BC.

Ussher's proposed date of creation was close to that calculated by his contemporaries, including such luminaries as Johannes Kepler and Isaac Newton. Some pointed to 2 Peter 3:8, which states that "one day is with the Lord as a thousand years, and a thousand years as one day." This ratio was tied to the six days of creation in the book of Genesis, leading them to conclude that the total lifespan of the world was 6,000 years. When Ussher published his chronology, he convinced a significant portion of Europe's leading scholars to conclude that the universe had just 342 years to go.

Steno never publicly renounced this Biblical time frame, but his geological investigations clearly challenged it. How could an honest person looking at, say, the Alps, explain the immense movement of rock, the folding, faulting, and erosion of land, the depositing of sedimentary strata, in the span of just 56 centuries? Alternatively if God created the earth's surface in its present form and then created plants and animals, how, exactly, did their remains wind up embedded inside solid rock?

It would be a long time before fundamental questions about our planet would be satisfactorily answered. It was only in 1956 that geochemist Clair Patterson, using lead isotopic data from a meteorite, concluded that the earth was about 4.5 billion years old. As Bill Bryson noted in "A Short History of Nearly Everything," Human beings would split the atom and invent television, nylon, and instant coffee before they could figure out the age of their own planet."

Just as the findings of Copernicus and the astronomers that followed him revealed that the earth is not the hub of the universe, Steno's revolution dislodged humanity from the center of our planet's history. As Bryson notes, if you imagine the past 4.5 billion years compressed into a single 24-hour period, the dinosaurs don't arrive on the scene until about 11 p.m. Anatomically modern Homo sapiens would emerge at one minute and 17 seconds before midnight. All of recorded history, from the Bronze Age to the Digital Age, would span a few seconds at the most.

Some might find this notion of an ancient earth profoundly alienating, but Steno's observations only served to deepen his religious convictions. Raised as a Lutheran, he converted to Catholicism in 1667, later becoming a priest, and ultimately a bishop who renounced the world and embraced poverty, ministering to Catholic minorities in northern Europe. The scientist who had been hosted by Europe's most opulent courts had transformed into an emaciated ascetic with few possessions other than a cloak, tattered habit, and two sackcloth shirts.

Three centuries after his birth, a group of Danish pilgrims appealed to the Vatican to have Steno canonized. On October 23, 1988, exactly 5,992 years after Archbishop Ussher's proposed date of creation, Pope John Paul II held mass of beatification for Steno, who is now known to Catholics as Blessed Nicolas Steno. Beatification is the final step before becoming a saint.

Steno was by no means the only Catholic cleric whose observations created models that counter literal Biblical accounts of creation. Gregor Mendel, an Augustinian friar, developed a model of inheritance that made Darwin's theory of evolution intelligible. In the 20th century, it was a Belgian priest, Georges Lemaître, who first proposed the Big Bang theory.

As for Steno, his legacy extends well beyond his contributions to anatomy and geoscience. His refusal to accept the authority of books, not even established science texts, not even sacred texts, lay at the heart of the then-emerging scientific method and its commitment to empirical observation and experimentation.

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For Steno, this commitment was suffused with piety. As he wrote in 1659: "One sins against the majesty of God by being unwilling to look into nature's own works."