Nicolaus Steno

Danish scientist and bishop

• Born: January 11, 1638
• Birthplace: Copenhagen, Denmark
• Died: December 5, 1686
• Place of death: Schwerin (now in Germany)

Considered by many to be the founder of geology, Steno provided scientific explanations for the existence of fossils, stratification, and the constancy of crystal angles. As an anatomist, he made important discoveries regarding glands, muscles, the heart, and the brain. As a bishop, he was a missionary to Catholics in Protestant lands.

Early Life

While the Thirty Years’ War (1618-1648) was convulsing Europe, Niels Stensen, who later Latinized his name to Nicolaus Steno (nihk-eh-LAY-uhs STAY-noh), was born on New Year’s Day, 1638, according to the Protestant calendar, but on January 11, according to the Catholic Gregorian calendar. His Lutheran father, Sten Pedersen, was a successful goldsmith who counted the king as one of his customers. His mother, Anne Nielsdatter, had, like her husband, been previously married and widowed.

Because of a severe illness, Niels was homebound until he was six years old. His full recovery was followed by the sudden death of his father. His mother remarried, but this husband died within a year. Niels’s half sister and her husband took over his care. He attended a Lutheran academy, where he was taught Latin and introduced to chemical experimentation.

Niels pursued his education at a difficult time in Denmark. When he was sixteen, a plague caused the deaths of one-third of Copenhagen’s population and, throughout most of his time at the University of Copenhagen, the city was under siege by the Swedes. Nevertheless, the young medical student was able to learn anatomy from Thomas Bartholin and, through his private studies, absorb the new ideas of such scientists as Galileo and René Descartes . Because of the chaotic situation in Copenhagen, Steno was unable to get his degree, and in the fall of 1659, carrying a letter of introduction from Bartholin, he traveled throughout Germany for several months before arriving in Amsterdam in the spring of 1660. Here, and three months later, in Leiden, he continued his medical education and began his first medical research.

Life’s Work

In Amsterdam, while studying with the anatomist Gerhard Blasius, Steno made his first important discovery. While dissecting a sheep’s head, he found an oral cavity that proved to be a source of saliva. This duct of the parotid gland became known as Steno’s duct (ductus Stenonianus). After Steno matriculated into the University of Leiden, he performed other dissections, some of which resulted in new discoveries. One such discovery was the tear-producing glands of the eyes. In 1662, he published a book summarizing his anatomical experiments on glands, called De musculis et glandulis observationum specimen (English translation, 1664).

The death of his stepfather in 1663 occasioned his return to Copenhagen, but when he was denied a position at the university, he traveled to Paris. In 1664, still in Paris, he received his medical degree, in absentia, from the University of Leiden. Melchisedec Thévenot, a wealthy government official, supported Steno’s work on muscles and the brain. An invitation to become court physician to the grand dukeFerdinand II de’ Medici in Florence led him away from France in 1665.

For his first two years in Italy, he worked at the Hospital of Santa Maria Novella on muscles, brain anatomy, and embryology. Using a microscope, he observed muscles as bundles of geometric units, each subdivided into fibrils. In 1667, he published a book called Elementorum myologiae specimen (Specimen of Elements of Myology , 1994) on his geometric description of muscles, explaining muscle contraction as an aggregation of the tensile forces in each unit. He also recognized that the heart is basically a muscle, which contradicted ancient authorities who saw the heart as the “home of the soul.” He published his findings as Nova musculorum & cordis fabrica in 1663 (New Structure of the Muscles and Heart , 1994). Steno once told friends that his conversion to Roman Catholicism occurred during the evening of All Souls’ Day, November 2, 1667, when, through the voice of a woman from whom he was asking directions, he heard God telling him to “cross over” from Lutheranism to Catholicism. His conversion marked a turning point in his life. Steno also believed in the wisdom of the Creator. That is, that God (the Creator) made human beings and made Earth as their home.

In 1669, he published his discourse on the anatomy of the brain, in which he criticized Descartes’s writings on the nature of humanity and the soul. For example, Descartes believed that the soul was connected to the body through the pineal gland in the brain, but Steno pointed out that animals other than humans had pineal glands. During the late 1660’s, he also conducted embryological research, helping to establish that not only do oviparous creatures produce eggs but also females of viviparous species. His discoveries in embryology were published in the 1670’s.

Many scholars consider Steno’s work in geology, paleontology, and crystallography to be his most significant. His studies in geology were initiated in the fall of 1667 when he dissected the head of a great white shark that had been clubbed to death on the coast of Leghorn (Livorno). Steno was particularly impressed by the number and structure of the shark’s teeth. In his report to Duke Ferdinand, he noted the similarities between the shark’s teeth and the “tongue stones” (glossopetrae) common in Tuscany and elsewhere. He proposed that these tongue stones were fossilized shark’s teeth. The mineralized shark’s teeth piqued his curiosity about other fossils, such as seashells found on mountains, and for the next eighteen months he traveled throughout Tuscany, making observations of rock layers, collecting fossils, and visiting quarries, caves, mines, and private geological collections. The result of his studies was his greatest work, De solido intra solidum naturaliter contento dissertationis prodromus (1669; The Prodromus to a Dissertation Concerning Solids Naturally Contained Within Solids, 1671; better known as the Prodromus ).

The book was meant to be the prelude to a much larger geological treatise, which he never wrote, but the observations, ideas, and theories that the Prodromus contained were important breakthroughs. In this treatise, Steno explained that if seashells were found in any rock layer (stratum), then an ocean must have been there at some time in Earth’s history. He then enunciated some of the basic axioms of stratigraphy, including the principle of superposition: In undisturbed stratified rocks, the lowest layers represent the first to be deposited and the top layers represent the most recent. He also believed that the geological history of Tuscany passed through various phases of submersion under the sea and uplift above it. When Tuscany was first submerged, rocks that were not fossiliferous (that is, not containing fossils) were deposited. After uplift, the land was fractured into mountains and valleys. During the second submersion, sedimentation was fossiliferous, and when the land reappeared, cavities in the underlying rock foundation often collapsed, only to be later eroded by flowing water. In this treatise, Steno also included an interesting section on crystals, in which he stated that crystal faces of a specific mineral have characteristically constant angles (modern crystallographers call this Steno’s law).

While Steno was writing the Prodromus, he received an invitation from Danish king Frederick to serve in his court, but before reaching Copenhagen, he learned, in February of 1670, that the king had died. He also received word that his patron, Ferdinand, was gravely ill, and by the time he returned to Florence, the grand duke was dead. The new grand duke, Cosimo III de’ Medici, was more interested in religion than science, but because he admired Steno’s piety, he gave him a villa on the Arno River where he pursued his geological studies. Two years after his return to Florence, Steno’s geological research was once again interrupted by another summons to Denmark, which Steno reluctantly accepted. In the winter of 1673 in Copenhagen, Steno gave his final public lecture on science. He had come to feel that as beautiful as science was, what was most beautiful to him was the spiritual world, so he decided to become a priest.

Because of his excellent education, he did not need to attend a seminary, and in April, 1675, four months after his return to Italy from Denmark, he was ordained and said his first Mass on Easter. He served as confessor to Cosimo III and did pastoral work in Florence, but in the spring of 1677, he was called to Rome so that he could be consecrated a bishop by Pope Innocent XI. His titular see was Titiopolis in Asia Minor (now Turkey), but instead, at the request of Duke Johann Friedrich of Hanover, Steno became apostolic vicar for the Nordic Missions. With a base in Hannover, he served as bishop for the small number of Catholics in northern Germany, Denmark, and Norway.

The Catholic duke Friedrich was followed as duke, upon his death, by his Lutheran brother, Ernst August, and Steno moved to Munster, where he instituted many reforms. His high standards, however, created enemies, so he moved to Hamburg, where his extreme asceticism and emphasis on poverty produced critics as well as admirers. He wrote religious works, exhorting clergy and laity to imitate Jesus Christ. After two years in Hamburg, he spent the remainder of his life in Schwerin, about 75 miles east of Hamburg. His harsh ascetic practices weakened his failing health, and, after his final confession, he died on the morning of December 5, 1686. Following Steno’s death, Cosimo III had his remains transferred to Florence, where Steno was laid to rest in San Lorenzo Basilica.

Significance

Historians of medicine have praised Steno’s skills as an anatomist, but his most important achievements were in geology. Stephen Jay Gould, a twentieth-century American evolutionary biologist, described Steno as “the founder of geology.” Steno’s principles of original horizontality and superposition marked the beginning of stratigraphy. His recognition of fossils as remnants of ancient organisms helped elucidate the history of fossil-bearing rocks.

Critics have pointed out that, despite Steno’s introduction of the chronological study of Earth’s history, he had a weak understanding of the massive length of geological time. Because he was influenced by the prevailing theological analysis of biblical chronology, Steno thought that Earth was only several thousand years old. However, unlike Galileo, he did not suffer persecution for his scientific ideas, and Church censors found nothing problematic with his Prodromus. He himself saw no contradiction between his scientific and religious work, since the human body and Earth were both creations of God, just as the Bible was inspired by God.

As a scientist and a bishop, Steno was dedicated to the pursuit of truth. He influenced scientists because of his discoveries in anatomy and geology, and he influenced Christians because of his striving for holiness. In 1988, with twenty thousand scientists, priests, and admirers of Steno in attendance, Pope John Paul II beatified the priest-scientist in St. Peter’s Basilica.

Bibliography

Cutler, Alan. The Seashell on the Mountaintop: How Nicolaus Steno Solved an Ancient Mystery and Created a Science of the Earth. New York: Penguin Plume, 2004. This work, intended for general readers, is both a biography of Steno and an analysis of his contributions to geology. Includes illustrations, a section on sources, and an index.

Kermit, Hans. Niels Stensen, 1638-1686: The Scientist Who Was Beatified. Leominster, Herefordshire, England: Gracewing, 2003. Although this work might be difficult to obtain, it is nevertheless a worthy biography of Steno as a religious leader. Includes illustrations, a bibliography, and an index.

Moe, Harald. Nicolaus Steno, An Illustrated Biography: His Tireless Pursuit of Knowledge, His Genius, His Quest for the Absolute. Translated by David Stoner. Copenhagen, Denmark: Rhodos, 1994. This biography tends to be hagiographical, but the text and illustrations provide general readers with an account of the positive achievements of Steno’s life and work as well as the complexities of his character and times.

Oldroyd, David R. Thinking About the Earth: A History of Ideas in Geology. Cambridge, Mass.: Harvard University Press, 1996. Considered by many scholars to be the most comprehensive overview of the history of earth sciences. Oldroyd analyzes Steno’s work as a significant part of this history. Index.