Nicolas Steno (in Danish, Niels Stensen) (1638 - 1686) was a pioneer both in anatomy and in geology.

After having completed his university education in Copenhagen, the city of his birth, he set out travelling in Europe; in fact, he would be on the move for the rest of his life. In the Netherlands, France, and Italy he came into contact with prominent physicians and scientists, and thanks to his eminent power of observation he very soon made important discoveries. At a time when scientific studies consisted in reading the ancient authorities, Steno was bold enough to trust his own eyes, even when his observations differed from traditional doctrines.

He recognized the nature of fossilized shark's teeth and snails from mountaintops and went on to explain the origin of fossils. He is credited with the principle of superposition, the principle of original horizontality, and the principle of lateral continuity: three defining principles of the science of geology of sedimentary rocks. He published his geologic studies in De solido intra solidum naturaliter contento dissertationis prodromus, or Preliminary discourse to a dissertation on a solid body naturally contained within a solid.

This mindset also was important for his religious views. Having been brought up in the Lutheran faith, he nevertheless questioned its teachings, something which became for him a burning issue when confronted with Roman Catholicism while studying in Florence. After theological studies, not the least the Church Fathers, he decided that the Catholic, not the Lutheran, church was the authentic church, and as a consequence he converted to the Roman church.

This, however, gradually made him put aside his scientific studies. (Possibly, his remarkable insight in geology made him realise that the formation of the Earth's strata could not be brought into agreement with the creation stories in Genesis - stories which nobody at the time dared to question.) He was ordained priest, later bishop, and sent to the "missions" in Lutheran North Germany. Here, after years filled with difficult tasks, he died after much suffering at Schwerin in 1686.

His life and work have been intensely studied, in particular since the late 19th century, and especially his piety and virtue has been evaluated with a view to an eventual canonization. In 1987, he was declared "beatus" - the first step to being declared "saint" - by Pope John Paul II. He is thus now called Blessed Nicolas Steno.

The Steno Museum in Århus, Denmark is named after Steno. It holds exhibitions on the history of science and the history of medicine. It also operates a planetarium and a medical herb garden.

Books

• Concerning Solids naturally contained within solids (1671)
• Elementary Mylogical Specimens (1669)
• Anatomical Observations (1662)
• Of the anatomy of the Brain (1671)

References

• The Seashell on the Mountaintop: A Story of Science, Sainthood, and the Humble Genius Who Discovered a New History of the Earth by Alan Cutler, 2003 ISBN 0525947086
• Steno
• Niels Stensen