In 1671, two years after its publication in Italy, De solido reached England. Members of the Royal Society of London, later known as one of the worlds most prestigious scientific bodies, quickly took notice. Henry Oldenburg, the societys secretary, had the work translated into English, and it was soon passed to the polymath Robert Hooke for review. Hooke had reached conclusions similar to Stenos about the origins of fossils, and the two could have become intellectual allies, but that didnt happen. Brilliant but grouchy, Hooke accused Oldenburga long-time thorn in his sideof slipping his hypotheses to Steno. Hookes accusations were soon eclipsed by a published attack from another Royal Society member, a physician named Martin Lister.
Although Steno had provided a strong argument for the organic origin of fossils, he had made no real progress in determining the nature of tricky fossils, those that bore no resemblance to currently living organisms. Lister offered a prime example: ammonites. Relatives of modern cephalopods, ammonites bore some resemblances to the modern nautilus, but also striking differences. There was an explanation for this, one already suspected by the contentious Hooke: the ammonites differed so much from living mollusks because ammonites were extinct. But 17th-century Europe wasnt ready for the notion of extinction; the concept would not achieve scientific respectability until the turn of the 19th century when it was articulated by the great French naturalist Georges Cuvier.
Listers criticisms must have been unpleasant, but the support of John Woodward was worse. Woodward was a successful physician and Royal Society member. After Stenos death, he usedplagiarized, in factmany of Stenos arguments to bolster his own interpretation of Noahs Flood during which, Woodward claimed, Newtonian gravity was suspended, causing the Earths solid matter to instantly shiver into millions of Atoms and relapse into its primitive Confusion.
The setbacks, however, proved temporary. In the 18th century, De solido was reprinted at least twice, in Latin and French, and miners and mineral surveyors began applying Stenos principles to their work. By regarding the lowest rocks as the oldest and the highest rocks as the newest, an Italian miner named Giovanni Arduino classified the rock layers of the Alps into three categories. Primary rocks were the oldest and had no fossils. Secondary rocks consisted of tilted sedimentary layers with fossils. Tertiary rocks included still-horizontal sedimentary rocks, also containing fossils. Arduino didnt relate these rock groups to biblical events, though they became linked in popular use, most people assuming that Secondary rocks resulted from Noahs Flood.
As Stenos principles gained acceptance, however, they began to undermine the biblical chronology he had believed. In 1720, chemist René Réaumur published a description of sediment layers composed mostly of broken shells. Because many of these layers were several meters thick, he argued that they could not have been deposited by a flood lasting, as the Bible described Noahs Flood, less than a year. By the late 18th century, some geologists had also begun to question the antiquity of humankind compared to other forms of life. In deeper and therefore older sediment layers, they found relics of Noahs Flood which, according to the Old Testament, happened after the creation of humans. So they should have found human remains in the older rock layers, too, but they didnt; human remains appeared only in the youngest rocks. Even more amazing, fossil collectors found a menagerie of remainsof marine and flying reptiles, oddly-proportioned mammals, and a huge variety of invertebratesrecorded nowhere in history. An astonishing succession of life forms had apparently come and gone before humans arrived on the planet. By the close of the 18th century, the famous French naturalist Georges Buffon publicly described humans as recent arrivals on a planet roughly 75,000 years old. Privately, he estimated the planets age at closer to 10 million years. No one would know the Earths age until the 20th century, after the discovery of radioactivity enabled scientists to attach absolute ages to rocks. (In 1953, two independent studies estimated the age of the Earth at approximately 4.5 billion years.) Yet because of Stenos principles, scientists could arrange fossils chronologically, and even locate rich seams of fossil fuel to power the 19th and 20th centuries.
The eventual discoveries of geology were all unimaginable to the 17th-century savant. Although King Frederick III died before Steno reached Copenhagen, the savant wound up there anyway. Steno missed Florence, and after two years, he petitioned the new monarch for permission to return. Permission granted, Steno returned to Tuscany and tutored a young Medici prince, but he wasnt satisfied. In 1675, Steno took a vow of poverty and became a priest. He hoped for a simple life of pastoral duties, but the Catholic Church summoned him to Rome and made him a bishop in 1677. His new assignment was in northern Europe, converting Protestants to Catholicism in Germany, Norway, and Denmark. It was a tough assignment, and as before, he missed Florence.
Steno took his vow of poverty seriously, and acquaintances watched in dismay as he grew skinnier. A friend he had recently converted recounted finding Steno without a house, without a servant, devoid of all lifes comforts, lean, pale and emaciated. Over time, Stenos self-denial took its toll, and he died at the age of 48. Three centuries after his birth, a group of Danish pilgrims appealed to Pope Pius XI to name him a saint. Pope John Paul II beatified Steno in 1988, putting the 17th-century savant on the road to sainthood.
In the last years of his life, Steno cared more about saving souls than studying rock strata, yet he never renounced his scientific work. Steno certainly could not have imagined where his geologic principles would lead over the next three centuries. Likewise, succeeding geologists, paleontologists, and even anatomists would have had a hard time imagining their fields of research without his pioneering insights.