Carl Linnaeus believed that the fruit of the Tree of Knowledge was not an apple but a banana. He came to this conclusion in 1737, while studying plant specimens at Hartecamp, the estate of George Clifford, a wealthy Dutch banker and director of the Dutch East India Company. Clifford collected exotic plants from around the world and had succeeded in getting a banana plant to flower and bear fruit in his greenhouse. Linnaeus’ belief in the theological significance of the banana is enshrined in the name he gave it: Musa paradisiaca.

Today, one would be hardpressed to find someone willing to argue the banana’s case as the original forbidden fruit, although in the 18th century, there were many who took such theories seriously. The form in which Linnaeus expressed his belief in the banana’s paradisiacal origins, however, is still firmly entrenched in scientific practice. Three hundred years after the great Swedish naturalist’s birth, scientists the world over are still using the system he invented to classify plants and animals.

Harvard’s Museum of Natural History (HMNH) has mounted an exhibition to commemorate Linnaeus’ 300th anniversary and the system of binomial nomenclature he invented. While small, the exhibition brings to life the man of whom the philosopher Jean-Jacques Rousseau said, “I know of no greater man on earth.”

Born on a farm in southern Sweden, Linnaeus was expected to follow in the footsteps of his clergyman father, but from an early age he was fascinated by nature. He went to the University of Uppsala to study medicine, which at that time included a course in botany.

Linnaeus’ studies led him to the conclusion that the scientific investigation of nature was being hampered by the lack of a consistent taxonomy of the natural world.

“There were different systems in use at the time,” said Janis Sacco, the museum’s director of exhibitions. “Some were ecological, based on the idea that organisms that existed in the same habitat must be related to one another. Linnaeus believed that there should be a regular, systematic way of identifying what something is by comparing it to something else.”

His solution to the problem was a hierarchical system beginning with three kingdoms (animals, plants, and minerals), and branching out from there into classes, orders, genera, and species. The groupings were based on the similarity of physical characteristics. He used Latin names because Latin was the universal language of learning, familiar to all educated Europeans.

“Systema Naturae,” the 11-page pamphlet in which Linnaeus first introduced his system, appeared in 1735. Linnaeus’ personal copy, replete with his hand-written notations, will be on display at the HMNH Nov. 6. This one-day appearance will be the only public showing of the unique volume in New England. The exhibition also includes a copy of the book’s 10th edition, which had grown by 1758 to include 4,400 species of animals and 7,700 species of plants.

A highly religious man (although arguably not a humble one), Linnaeus believed that he had been put on earth to classify nature according to the order that God had originally intended. He took as his motto “Deus creavit, Linnaeus disposuit” (God created, Linnaeus organized).

But despite his piety, Linnaeus’ commitment to classifying organisms according to observed characteristics sometimes got him into trouble with religious authorities. His classification of humans as animals that bear obvious similarities to apes and monkeys scandalized theologians.

Not that Linnaeus was asserting or even implying that humans developed from monkeys. There was no notion in his system of one species developing or evolving from another. That idea was still a hundred years in the future. Linnaeus, along with all naturalists of his time, subscribed to the idea that every living thing on earth had been created by God in the course of a single week and had not changed since then.

And yet, simply by arranging organisms according to a logical order based on physical characteristics, Linnaeus laid the groundwork for the insights of Charles Darwin a century later.

“He wasn’t an evolutionist, but he set the stage for evolutionary theory,” said Sacco.

Linnaeus made several collecting expeditions over the course of his life, including one to Lapland, where he identified and named the reindeer. He never traveled beyond northern Europe, however, and most of the specimens he named were brought to him by explorers returning from more distant lands. As a professor at the University of Uppsala, he was assisted by an ever-growing team of assistants, whom he referred to as “the disciples.” A small, wiry man with indefatigable energy, he lived until 1778 and wrote 70 books and 300 scientific papers over the course of his life.

Since his time, biologists have revised many of his classifications, based on subsequent discoveries and more sophisticated observation methods. The use of DNA analysis has added a whole new dimension to the search for relationships among organisms. But the basic structure of his system remains virtually unchanged.

“His work is considered the cornerstone of systematic biology,” Sacco said. “He was just dealing with the ‘what.’ The ‘why’ and the ‘how’ he left to others.”