For two years in the late 1970s I followed in the footsteps of Carl Linnaeus: I toiled in the field of taxonomy. The small corner of nature's jigsaw puzzle that I tackled was a group of marine sponges whose baffling variability defied easy classification. I considered their color and form, examined their skeletal architecture, counted their spicules, noted the shape of their larvae, and pondered which of these characters could be used to separate my subjects into meaningful categories.

My youthful foray, long since abandoned, resulted in a classification scheme for 43 species of New Zealand sponge. It also gave me an appreciation for the towering achievement of Carl Linnaeus, the father of modern taxonomy. Linnaeus, born 300 years ago this month, classified and named more than 4,000 animals and nearly 8,000 plants. As superhuman a feat as that was, the illustrious Swede also devised the very system of classification that I and every other student of taxonomy have used since then.

The eldest son of a small-town curate, Linnaeus chose to pursue his father's recreational interest in plants and became the greatest botanist of his time. He was also a successful physician, a charismatic lecturer, a devoted mentor, an enthusiastic gardener and a prolific writer. He not only sorted and systematized all the known species of his day but also pioneered the study of how indigenous people use plants for medical and other purposes, earning another sobriquet: the father of ethnobotany. The simplicity and logic of his taxonomic system made natural history accessible to amateurs, ushering in the Victorian passion for nature. Jean Jacques Rousseau said of him, "I know no greater man on earth."

Prior to Linnaeus, taxonomy had been a shambles. There were complex names for even the commonest species, and multiple criteria for classifying them. The tomato, for example, was Solanum caule inermi herbaceo, foliis pinnatis incises—the solanum with the smooth stem which is herbaceous and has incised pinnate leaves. Linnaeus' genius was to apply the social hierarchy of his day, with its kingdoms, provinces, parishes and villages, to the natural world. He slotted plants and animals into a framework of five main categories—kingdom, class, order, genus, species. Almost incidental to his encyclopedic audit of the natural world was his decision to call each living thing by just two Latin names, representing genus and species. This innovation, known as binomial nomenclature, has proved to be Linnaeus' greatest gift to posterity. Any time Homo sapiens mention Felix domestica (the house cat) or Lycopersicon esculentum (the tomato) or Callyspongia ramosa (one of my beloved sponges) Linnaeus' naming system is invoked. Out of the babel of competing nomenclatures he forged a single, universally applicable scientific language.

At times, Linnaeus thought of himself as the second Adam. "Deus creavit, Linnaeus disposuit," he liked to say—God created, Linnaeus organized. The frontispiece of his Systema naturae, his magnum opus, depicts its author in the Garden of Eden, evidently applying Linnaean names to freshly minted creatures. First published in 1735 as an 11-page tract, Systema naturae was Linnaeus' tabulation of the three recognized realms of nature: animals, plants and minerals. He kept adding to it throughout his life, and when the 13th edition was published in 1770, eight years before his death, it had grown to 3,000 pages. It was the last species omnibus ever attempted by a single person. Such was the proliferation of scientific discovery after Linnaeus (in part because his classification system was so comprehensive and easy to use) that no one individual could ever again hope to take nature's measure.

But how much longer will the Linnaean system last? Recently it has come under attack from some taxonomists who believe its structure is too inflexible to cope with the explosion of knowledge unleashed by DNA analysis. Today's young Turks of taxonomy want to abolish the strict ranked hierarchy of family, order, class, etc. In its place they advocate "clades," groupings that are based on genetic relationships and can be expanded, contracted or redefined as new kinships are discovered. For now, the traditionalists outnumber the iconoclasts, and Linnaean-style classification remains the gold standard.

Linnaeus struggled to find universally applicable characters by which to categorize the myriad manifestations of life. In classifying plants, Linnaeus chose to focus on sexual characteristics. He placed plants into classes according to the number, length and distinctive features of their pollen-bearing stamens, and into orders according to their pistils.

The approach earned Linnaeus the ire of his more prudish colleagues. They objected to his lyrical descriptions of the love lives of plants. Bad enough that a flower's petals should be compared to the "bridal bed...perfumed with so many sweet scents in order that the bridegroom and bride may therein celebrate their nuptials with the greater solemnity," but when Linnaeus defined polyandrous flowers as having "twenty males or more in the same bed as the female," this was too much. "Who would have thought that bluebells and lilies and onions could be up to such immorality?" jibed one critic, who dismissed the entire system as "loathsome harlotry" unworthy of the Creator.

For animals, Linnaeus' criteria were less provocative. He grouped mammals according to teeth, toes and teats; fish by fin bones; insects by wings; and birds by feet and beaks. He recognized that his categories for plants and animals were arbitrary and his classification no more than a crude stab at divining nature's pattern, but they would have to do. Despite their shortcomings, Linnaeus' names for the roughly 12,000 organisms he examined over the course of his life became the starting point for biological classification.

Linnaeus' theories and methods were always rooted in the real world. At a time when taxonomists were largely an indoor species, inhabiting lecture halls and libraries and scrutinizing pressed flowers, pinned insects and pickled vertebrates, Linnaeus was a dirt-under-the-fingernails scientist. For more than 20 years he conducted public excursions in the countryside around Uppsala—possibly the world's first guided nature walks. He did so partly to supplement the income from his impecunious postings as curator of the Uppsala botanical garden and then as professor of medicine at Uppsala University. Participants (as many as 300 per excursion) paid him in whatever currency they could afford: coins, hats, socks, books, buttons.

What forays they must have been! Botanizing with Linnaeus would have been the equivalent of studying geometry with Euclid, or taking a writing class with Shakespeare. In keeping with Linnaeus' orderly disposition, the expeditions were organized with the precision of a military campaign, with designated note takers, specimen collectors and bird shooters. A bugle would sound when rare species were found. At the end of the ramble—up to 12 hours during the Baltic summer months—the party would troop back to town, waving banners, blowing horns and beating kettledrums. At the botanic garden a shout would go up, "Vivat Linnaeus!"

In later years—after the rector of Uppsala University protested—these "inquisitions of the pastures," as Linnaeus called them, had to be curtailed. "We Swedes are a serious and slow-witted people," the rector explained. "We cannot, like others, unite the pleasurable and fun with the serious and useful."

In 1732, Linnaeus made a collecting journey that would influence his thinking for the rest of his life. Lapland, the glacier-carved Arctic region that caps Scandinavia, was for Linnaeus what the Galápagos Islands were for Darwin—a notional seed pearl around which layers of theory would be laid.

Linnaeus set out alone on horseback from Uppsala the day before his 25th birthday, equipped with little more than a plant press, a gun, a hand lens and a change of clothes. His aim was not just to collect specimens from Sweden's land of the midnight sun but to learn how the "happy Lapps"—indigenous Sami people—and Swedish and Finnish homesteaders made use of them. It was arguably the world's first ethnobotanical expedition.

To stretch the limited funds he had been given by the Swedish Royal Society of Science to make the journey, Linnaeus adopted the local lifestyle, including eating reindeer tongues. He admired the Lapps' resourcefulness. They baked bread from fir bark, pine needles, dried fish, moss and seaweed. They had 18 ways of using milk, including "fresh boiled and coagulated with beer" and "mixed with sorrel leaves and preserved till winter in the stomach of a reindeer."

His diary is filled with a young man's ebullience. Charmed by the sight of bog rosemary in full bloom, its blossoms the color of "a fine female complexion," he thinks of Andromeda chained to her watery rock, and decides to give the plant genus that name. On learning that Sami bachelors carry about pieces of sweet-smelling fungus as a kind of cologne-cum-aphrodisiac, he exclaims, "O whimsical Venus! In other parts of the world you must be wooed with coffee and chocolate, preserves and sweets, wines and dainties, jewels and pearl...here you are satisfied with a little withered fungus."

As he traveled and collected—discovering and eventually naming over 100 new species—his thoughts turned to the floristic differences between Lapland and the rest of Sweden, and to the benefits that would accrue if species could be swapped between the two regions. But why stop at botanical rearrangement within the country, Linnaeus wondered; why not borrow from "God's endless larder" elsewhere in the world?

Other nations had overseas colonies that supplied them with goods they couldn't produce at home; Sweden could go one better by cultivating the crops of the world within its own territory. Linnaeus believed that acclimatization, the process by which organisms become habituated to a new environment, could be the engine of economic growth for his "dearest Fatherland." As his most recent biographer, Lisbet Koerner, writes in Linnaeus: Nature and Nation, the proud Swede sought to "re-create within his national borders a trans-oceanic empire."

Back in Uppsala, fired by patriotic zeal and a naive confidence in the adaptability of nature, he became obsessed with the idea of cinnamon groves and tea plantations flourishing under a Baltic sun. Unswerving in his belief that any plant could be "tamed" to withstand a more rigorous climate, he looked to a day when fashionable Europeans would wear Swedish silk, drink Swedish coffee and eat Swedish rice.

Ultimately, Linnaeus was mistaken in his view that plants are globally interchangeable—a conclusion he reluctantly came to accept after most of his horticultural transplants failed. (A notable exception was rhubarb, a native of Asia, whose introduction to Sweden was an achievement he took pride in.) Linnaeus was also wildly wrong about the number of living species. He thought there might be around 40,000 all told; estimates today range from 10 million to 100 million, most of which are microscopic.

Many of his ideas now seem ludicrous. He believed epilepsy could be caused by washing one's hair, and leprosy caught by eating herring worms. He persisted in the archaic belief that swallows wintered at the bottom of lakes. Others were quaint: he devised a clock based on the opening and closing times of various flowers.

But many of his other views were surprisingly modern. He foreshadowed Darwin in his belief in a universal struggle for survival. He was the first to classify human beings in the same genus as other primates, and he grouped whales with mammals (previously they had been considered fish). He advocated biological control as a means of dealing with insect pests (he was particularly keen to find the invertebrate "lion" that would control bedbugs), and he understood the importance of biodiversity: "I do not know how the world could persist gracefully if but a single animal species were to vanish from it," he wrote in his journal. He even conjectured that micro-organisms "smaller than the motes dancing in a beam of light" might be responsible for transmitting contagious diseases—long before medicine embraced the idea of pathogens. Linnaeus dabbled in aquaculture, successfully growing pearls in freshwater mussels. And he gave an important tweak to the Celsius scale of temperature measurement. Anders Celsius, a Linnaeus contemporary, had designated the boiling point of water to be 0 degrees and the freezing point to be 100. It was Linnaeus' idea to flip the scale.

Though he didn't follow his father into the ministry, Linnaeus remained a devout Lutheran throughout his life, despite the clash of his scientific views with his theological conclusions. Faith led him to believe that human beings are "candles in God's palace," reflecting the "creator's shining majesty." Science took him to a far bleaker conclusion. "Pathologically," he wrote, "you are a swollen bubble till you burst, dangling from a single strand of hair in one brief moment of fleeting time." The man who classified the living world even wondered why there was any diversity in nature at all. Why did the Creator not make the earth out of cheese, he mused, "which we worms could have gnawed while we grew up, lived, and multiplied?"

Linnaeus struggled with pendulum-like swings between exuberance and depression, ego and angst. At one moment he was God's chosen instrument, at the next a miserable failure. "Had I had rope and English courage," he wrote to a colleague, "I should long ago have hanged myself." Even when he was made a member of the Swedish nobility in 1762, taking the name von Linné, he chose as part of his heraldic emblem an unprepossessing Lapland flower called Linnaea borealis—a plant named after him. He describes the delicate species as "lowly, insignificant, disregarded, flowering but for a brief space," adding that it was named "from Linnaeus who resembles it."

His conception of a vengeful deity didn't help his equanimity. Ever the cataloger, he collated a file of some 200 instances of what he considered divine retribution meted out to errant mortals. Published after his death, Nemesis Divina pictures a fire-and-brimstone deity not unlike cartoonist Gary Larson's caricature of God at his computer, forefinger poised over the SMITE key. The self-doubting Linnaeus never outgrew his dread that the finger was about to fall.

During bouts of melancholy his family was a consolation (he was a devoted father to his seven children, five of whom survived early childhood), as were his pets, especially a guenon monkey called Diana and a raccoon named Sjubb. And he could always turn to his beloved plants for comfort: "I have no time to think of illness, Flora comes hastening with all her beautiful companions."

Such unquenchable joy in nature is one of the most appealing qualities of the man, and one of the reasons Swedes venerate him. This May 23, the annual Linnaeus Day, the streets of Uppsala will ring loudly with tercentennial tributes to the "flower king" of Scandinavia. I hope that the Uppsala cafés will revive the tradition of baking Linnaeus cream cakes, iced with his silhouette, and that there will be a celebratory bottling of Linnaeus liqueur. From my home in antipodean New Zealand—almost as far from Sweden as it is possible to be—I, too, will raise a glass (of aquavit) to the inventor of science's universal language, nature's chief librarian, and, as one of his contemporaries described him, "the most compleat naturalist the world has ever seen."

Vivat Linnaeus!

Kennedy Warne was the founding editor of New Zealand Geographic.