by Jack Lynch
Theophrastus’ greatest advance on previous botanical writers was the way he organized his material. Every science has to wrestle with classifying all the specimens that come under its purview, determining which qualities are what Aristotle called “essential,” and which merely “accidental”; it is only fitting that one of Aristotle’s schoolmates should be engaged in the effort. The key to a useful taxonomy consists of identifying the features that let us group like with like. For the geologist, which features—color, texture, hardness—make this rock like or unlike that rock? Should the meteorologist treat all the dark clouds as similar in kind, or all the fluffy clouds, or all the high clouds? The problems are especially challenging in the life sciences. Charles Darwin utterly rewrote plant and animal taxonomy by showing how variety in the natural world emerged from descent with variation, and modern scientists are able to use genetic analysis to confirm evolutionary descent. We can now put every living species into its proper kingdom, phylum, class, order, family, genus, and species. But without genetic tests, we run the risk of being misled by apparent similarities. If, for instance, we start by dividing animals into flying and nonflying, we end up with one group including most birds, many insects, flying fish, and flying squirrels, while chickens, ostriches, most fishes, and most squirrels are in the other group—somehow unsatisfying, because it also feels natural to keep the feathered animals together, all the fishes together, and so on. Flying, it seems, is an Aristotelian accident: most birds fly and most mammals do not, but the power of flight is not essential to being either bird or mammal.
TITLE: Περ φυτν στορα (On the history of plants)
COMPILER: Theophrastus (c. 371–c. 287 B.C.E.)
ORGANIZATION: Topical: book 1, plant anatomy; book 2, growth; book 3, wild trees; book 4, foreign plants; book 5, woody plants; book 6, shrubs; book 7, small herbs; book 8, cereals; book 9, medicinal plants
PUBLISHED: Between 350 and 287 B.C.E.
ENTRIES: More than 500 species
TOTAL WORDS: 100,000
Theophrastus had no conception of evolution or genetics, and he had to depend on naked-eye observation to see the deep connections. His task was even more difficult than classifying animals, because the features and behaviors of plants are less obvious to the untrained eye. The fact that some flowers are white, some pink, and some blue is merely accidental—they could just as easily be other colors—so a biological taxonomist should not make flower color an essential part of classification. Which qualities, though, do make each plant species what it really is? Should we put all the flowering plants in one group, the nonflowering plants in another? Keep the woody stems together? Are the grasses a distinct kind, or do many essentially different plants happen to look grassy?
Before Theophrastus, most plant classifications were based on human needs: plants were grouped based on their use as food or medicine, whether they were wild or cultivated, and so on. Theophrastus took a different approach and based his taxonomy on morphology or form. He used physical structure to define his four broadest categories: tree, shrub, half-shrub, and herb. He then went on to divide species all into flowering and nonflowering species—still an important distinction in botany. He went even further, dividing the flowering species into those with leafy flowers and those with capillary flowers, laying the groundwork for much later breakthroughs in petaliferous and apetalous flowers. He made important discoveries in the structure of flowers, though he did not understand that flowers were plants’ reproductive organs. A master of close observation, Theophrastus described the minute structures of small seeds at a time when even the magnifying glass was unknown. Still he described plant morphology, from root to fruit, in more detail than anyone before him, distinguishing permanent from transient features of plant biology.
The structure of Historia plantarum reflects this taxonomic understanding. Book 1 covered the anatomy of plants, including roots, fruits, seeds, leaves, flowers, and other parts. It lays out his four broad categories, while acknowledging there were complex cases that would test his boundaries. Book 2 moves on to the growth of plants from seeds, bulbs, or roots. Book 3, on wild trees, corrects conventional wisdom by insisting that trees do not emerge from spontaneous generation. In book 4, Theophrastus examines foreign trees and shrubs, with attention to the wider Mediterranean world. Wood in its many varieties is the subject of book 5, shrubs of book 6, small herbs of book 7, and cereals, beans, and peas of book 8. In his discussion of woods he describes which ones are best suited to timber and which ones work well in a lathe. Book 9 is devoted entirely to the use of plants as medicines, making it one of the oldest surviving herbals. Theophrastus did his best to sort reliable fact from superstition, and the result is a magisterial survey of the entire plant kingdom as it was known in fourth-century-B.C.E. Greece. It touches on more than five hundred plant species, the large majority of which are cultivated rather than wild plants—he says that most wild plants cannot be discussed because they have been neither identified nor named. Still, he was the first to recognize the existence of aerial roots, which are common in orchids, mangroves, banyan trees, and other species.
Scholars believe Theophrastus intended his work as a set of lecture notes, but before long it was being employed as a reference book. The entries are curt and include quick lists of related plants or features, designed for easy consultation. Almost any ancient investigator into the plant kingdom would begin with Theophrastus, navigating through his taxonomy and finding a specimen’s place in the larger scheme. And this decision to reduce the botanical world to a work of reference had lasting consequences. Because he devoted so much effort to a logical organization, one that was structured around the plants themselves rather than around human needs, his reference book served to turn attention outward to the natural world. He made the gathering of further information possible, because his collection revealed clearly where the gaps in knowledge were and signaled to the world where research might profitably proceed. Though Theophrastus’ work was lost and forgotten through most of the Middle Ages, its rediscovery at the beginning of the fifteenth century led to a series of editions and translations at just the time the West was beginning its scientific revolution.3
Theophrastus’ knowledge was daunting, but his most important successor in the ancient world makes even his polymathic range seem limited.
Gaius Plinius Secundus, better known as Pliny the Elder, was born in 23 C.E. at Como in the Italian Alps. He was schooled in Rome, by then as much the center of the intellectual world as Athens had been three and a half centuries earlier. Christianity was in its very earliest phases, and there is no evidence that it made any impression on Pliny. But Rome in the thirties and forties C.E. was a literary hot spot. Roman politics in the era was notoriously messy: the emperor Tiberius, who had effectively walked away from his duties after a coup, died in the year 37, leaving his great-nephew Caligula to become emperor; he was in turn assassinated after just four years. His uncle, Claudius, would take over until his own death in 54, when he was succeeded by his adopted son Nero.
This was the background to Pliny’s life, and the political turmoil was more relevant to his career than such things usually are for scientists. Pliny was above all a man of the world. He commanded a cavalry squadron in Germany, Gaul, and Spain. He was a friend and confidant of generals, politicians, even emperors. He was at the center of political and military power in the early Empire. Still he found time to write. Only one of his works survives, but we are lucky to have a reliable list of all the others, because he cataloged his life’s work in a letter to a friend: seven works, coming to a total of 102 scrolls (libri in Latin). He wrote on military matters, on grammar, and on Roman history, and he was an amazingly disciplined writer. Pliny’s nephew, also called Pliny, preserved this account of his uncle at work, describing his “keen intelligence, incredible devotion to study, and a remarkable capacity for dispensing with sleep.” The uncle would get up “long before daybreak” and work until two o’clock the next morning, p
ausing in his studies only to pay a visit to the emperor Vespasian. That devotion to his work was evident in everything he did: his only downtime was while he was in the bath, and even then he would have someone read to him. The same regime was in place at the dinner table:
Over his dinner a book was read aloud to him and notes were made, and that at a rapid pace. I remember that one of his friends, when the reader had rendered a passage badly, called him back and had it repeated; but my uncle said to him, “Surely you got the sense?” and on his nodding assent continued, “Then what did you call him back for? This interruption of yours has cost us ten more lines!” Such was his economy of time.
A traveling secretary read to him on the road, and he even chided his nephew for walking anywhere in Rome: had he taken a sedan chair, he could have used the time to do more reading. As his nephew summarized his guiding philosophy, “He thought all time not spent in study wasted.”4
Though Pliny read and wrote widely, he seems to have had scientific interests throughout his life. Historia naturalis means “natural history,” though the phrase usually means what we would think of as the observational sciences generally. As Tom McArthur wrote, Historia naturalis “could just as easily be interpreted in modern terms as General Knowledge.”5 Pliny and his readers would not have understood the fields he covered as part of some broader enterprise called “science”; they would have been more comfortable with the idea of “nature.” As a twentieth-century translator puts it, the Historia is “an encyclopaedia of astronomy, meteorology, geography, mineralogy, zoology, and botany, i.e. a systematic account of all the material objects that are not the product of man’s manufacture.”6
TITLE: Naturalis historia
COMPILER: Gaius Plinius Secundus (Pliny the Elder) (23–79 C.E.)
ORGANIZATION: Topical: book 1, introduction; book 2, cosmology and meteorology; books 3–6, geography; book 7, anthropology; books 8–11, zoology; books 12–27, botany; books 28–32, medical zoology; books 33–37, medicinal minerals
PUBLISHED: c. 77–79 C.E.
ENTRIES: 2,493
VOLUMES: 37
TOTAL WORDS: 395,000
Pliny’s introduction delimits his scope: the “sacred, eternal, immeasurable” is beyond our knowledge. “It is madness,” he wrote, “downright madness, to go out of that world, and to investigate what lies outside it just as if the whole of what is within it were already clearly known.”7 But everything else—everything—was fair game. He started with the elements, understood to be four: earth, air, fire, and water. He also gave not only astronomical observations but inferences and precise measurements:
It is unquestionable that the moon’s horns are always turned away from the sun, and that when waxing she faces east and when waning west; and that the moon shines 47½ minutes longer daily from the day after the new moon to full and 47½ minutes less daily to her wane, while within 14 degrees of the sun she is always invisible. This fact proves that the planets are of greater magnitude than the moon.8
Pliny was especially drawn to questions that were not yet settled. “There has been a great deal of minute enquiry among the learned,” he observed, “as to the manner in which bees reproduce their species; for sexual intercourse among them has never been observed.” He was even acute enough to notice evidence of seemingly vanished species, at a time when extinction was barely considered even as a possibility: “There is one thing at which I cannot sufficiently wonder—that of some trees the very memory has perished, and even the names recorded by authors have passed out of knowledge.”9
Unlike Theophrastus, who aspired to keep humankind out of his book, Pliny has a particular interest in the parts of the natural world with a bearing on human existence. In the historian and scholar Foster Stockwell’s account of Pliny, “nature serves humankind. Natural objects are invariably described in their relation to humans and not by themselves.”10 Some of his most energetic and detailed investigation into botany, for instance, deals with the grapevine, because wine was central to the Roman economy. From an attempt to reckon the number of varieties of grapes, he goes on to discuss the quality of the wines made from them—“some kinds of wine are more agreeable than others”—and from there to a discussion of the effects of alcohol on the body (“Wine has the property of heating the parts of the body when it is drunk and of cooling them when poured on them outside”), and then to a meditation on drunkenness (“Think of the drinking matches! think of the vessels engraved with scenes of adultery, as though tippling were not enough by itself to give lessons in licentiousness!”).11 There is even an account of the effects of temperature on already-fermented wine, a lesson that many liquor shops could stand to learn today.12
How much made it into the Historia naturalis? The eighteenth-century historian Edward Gibbon is not exaggerating when he calls it “that immense register, where Pliny has deposited the discoveries, the arts, and the errors of mankind.”13 Pliny claims to have covered twenty thousand “noteworthy facts” or “things of importance,” drawn from 473 authors and two thousand volumes—and a modern scholar calls this tally “a severe underestimate.”14 His compilation is one of the longest works to survive intact from the ancient world. Critics have noted faults, particularly that Pliny is too credulous of his sources.15 But the complaint is not entirely fair. The scientific method we take for granted was simply not a going concern in first-century Rome: no one was testing claims against reality. The job of a writer in antiquity was not to perform experiments but to weigh his sources, and here Pliny is exemplary. He was also unusually scrupulous about citing his sources, most of them Greek. He was genuinely interested in the claims of authority made by his sources, and he noticed that many facts related by “the most professedly reliable and modern writers” were actually copied verbatim from older writers.16
Pliny is in fact more scrupulous in testing his claims than most of his predecessors and contemporaries. Having disavowed any intention to talk about the spiritual, for instance, he occasionally paused to reclaim some phenomena for the natural world. “The common occurrences that we call rainbows,” he says, “have nothing miraculous or portentous about them, for they do not reliably portend even rain or fine weather. The obvious explanation of them is that a ray of the sun striking a hollow cloud has its point repelled and is reflected back to the sun, and that the diversified colouring is due to the mixture of clouds, fires and air.” The science is imperfect; the principles of the refraction of light would not be understood for more than sixteen hundred years. But the claim that rainbows are simply “common occurrences” is a milestone in the scientific understanding of the world. And even when he was at his least skeptical, he made it possible for later natural historians to supplement and correct his work. In this sense, even the credulous aping of superstition can contribute to the advancement of knowledge, because compilation on Pliny’s grand scale made it easier to know which claims need to be tested and which refuted. He knew perfectly well that much remained to be done: his book was the beginning of a process, not the end. “Nor do we doubt,” he wrote in his preface, “that there are many things that have escaped us also; for we are but human, and beset with duties, and we pursue this sort of interest in our spare moments.”17
His devotion to research eventually did him in. On August 20, 79 C.E., when Pliny was in command of a Roman fleet, the first in a series of earthquakes shook the Naples area. Pliny, ever the curious naturalist, felt obliged to investigate. On August 22, around noon, the earth shook again—this time accompanied by a formidable explosion. The top of Mount Vesuvius had blown off, and the emerging smoke took the form of a pine tree, with a vertical “trunk” and “branches” coming out at right angles. Pliny watched with his nephew from Misenum, far enough from Vesuvius to ensure his safety. But the scientific spirit made him long for a closer look. As soon as the volcano erupted, he did what few would have the courage to do: instead of running away, he sailed directly toward it. As stones and ash came raining down on the ships, the sailors were t
errified, but Pliny—as certain as ever that all time not spent in study was wasted—continued calmly dictating his latest work to a secretary by his side. He died in the shower of ash, a martyr to his scientific curiosity.
Pliny himself was asphyxiated, but the Historia naturalis lived on. Most of the other great natural historians of antiquity (such as Theophrastus) had written in Greek, a language almost unknown in medieval Europe before the fifteenth century.18 Even though most of his sources were Greek, Pliny’s decision to write in Latin made him one of the most widely read ancient “scientists” for more than a thousand years. Even after the Middle Ages, Pliny remained a vital presence. The Historia naturalis was put into print very shortly after Gutenberg’s invention of movable type: the first printed edition appeared in Venice in 1469, with another in 1476. This shows that there was real demand for a fifteen-hundred-year-old book at just the moment that modern scientific epistemology was developing. But in 1492, Niccolò Leoniceno, an Italian scholar and physician, published De Plinii et aliorum in medicina erroribus (On the medical mistakes of Pliny and others), which set off a debate among the scholars of Ferrara at the end of the fifteenth century. It took another two hundred years for most investigators to abandon Pliny as a serious primary source.
The volume of scientific information has increased by many orders of magnitude since Theophrastus and Pliny; the Roman’s twenty thousand “things of importance,” once a lifetime’s work, are now collected in seconds in many scientific experiments. And reference books have worked to stay current with the increases in knowledge. We’ll see scientific and medical encyclopedias scattered throughout this book. But the principles established by these classical writers—one focusing on the morphological features of his plant specimens, the other examining the relationships between the natural and the human worlds—established the pattern that scientific encyclopedists are still following.
