Hosack went, too.
HE WENT NOT FOR POLITICS but for medicine. Much as he appreciated his New York mentors, Philadelphia was home to the country’s best medical professors, who were teaching at the University of Pennsylvania’s medical school and on the College of Philadelphia’s medical faculty (the two institutions would merge in 1791). Among them was Benjamin Rush, the most famous physician in the nation. Rush’s approach to medicine was iconoclastic, empirical, and restlessly curious, making him the perfect teacher for the inquisitive Hosack.
Rush had been teaching and practicing medicine in Philadelphia since 1769. He had earned a reputation as the kind of man who was unafraid to shout his opinions from the rooftops. In 1773, he had published a blistering pamphlet on the evils of slavery. “Hear their cries, and see their looks of tenderness at each other upon being separated. . . . Let us fly to them to step in for their relief.” In 1776, he had signed his name to the Declaration of Independence, just above Benjamin Franklin’s. To Hosack’s joy, this eminent American scientist agreed to become his mentor, and he spent hours at Rush’s side—not only in class and in clinical settings but also as a frequent guest at the family dinner table. Hosack listened awestruck as Rush spoke in a “perpetual stream of eloquence.” Rush made the study of natural history sound romantic—it was, he said, “the first study of the father of mankind, in the garden of Eden.” Hosack memorized his mentor’s personal and professional habits and tried to emulate them. To maximize time and energy for teaching, medicine, and charity work, Rush arose early, ate sparingly, never touched alcohol, and read late into the night. He was no longer formally active in politics—insisting to Hosack that he was now a “mere spectator of all public events”—but in fact his home was always filled with government officials, naturalists, painters, and physicians. John Adams and Jefferson were Rush’s close friends, and he also knew President Washington well.
One towering figure among Rush’s friends was gone: Rush had been at Benjamin Franklin’s bedside as the latter lay dying in the spring of 1790. Hosack had arrived in Philadelphia six months too late to meet this legendary American. Still, nearly every subject he would study that year bore the imprint of Franklin’s curiosity and his passion for civic improvement. The Pennsylvania Hospital, where Hosack would receive clinical instruction, had been launched by Franklin in 1751. The medical school of the University of Pennsylvania—a university that owed its origins in large part to Franklin—held its lectures in a building that also housed Franklin’s celebrated American Philosophical Society, which brought together men keen on promoting “all philosophical Experiments that let Light into the Nature of Things” and thus “tend to increase the Power of Man over Matter, and multiply the Conveniencies or Pleasures of Life.” Franklin, spurred by the botanist John Bartram, had first floated the idea in 1743. The United States, Franklin argued, needed a forum where learned men could share their inquiries in botany, physics, chemistry, medicine, math, agriculture, and many other fields. By the time Hosack arrived in Philadelphia, the members included some of the nation’s most eminent men, among them Washington, Jefferson, and—very soon—Hamilton. Hosack began to dream of one day being elected to its ranks.
Philadelphia in 1790 was a noisy place fired by a new breed of citizens: the free leaders of a country they had forged themselves. Washington had gathered around him political figures matched in wits and clashing in vision. As these men hammered out the new national institutions, Philadelphia’s meeting halls, taverns, and printing houses rang with the shouts and laughter of a lively political culture. Hamilton, as secretary of the treasury, sought to strengthen the federal government through the creation of a powerful national bank, but Secretary of State Jefferson fought Hamilton hard, fearing the rise of a tyrannical central government that would trample the rights of the states. During the winter of 1790 to 1791, as Hosack hunched over his books and cadavers, Hamilton and Jefferson battled for George Washington’s approval—and the soul of the nation—just a block or two away, with Jefferson observing that he and Hamilton were “daily pitted in the Cabinet like two cocks.”
Hamilton prevailed over Jefferson, at least for the time being—in February 1791, the president signed Hamilton’s bank bill. Jefferson was despondent. By mid-May, he had arranged with Hamilton’s former ally Madison to make a temporary escape from Philadelphia on a botanical tour of New England. Jefferson loved plants. “What a field we have at our doors to signalize ourselves in!” he had recently exulted to the president of Harvard. “The botany of America is far from being exhausted.” He sketched out an itinerary for his trip with Madison that would take them up the Hudson River, then north into Vermont, and south again via Massachusetts. They met in New York and left town toward the end of May. When they reached the spot north of the city where the Hudson widens into a body of water that Dutch settlers had described as a sea (a zee), Jefferson began a travel journal: “May 21. Toppan sea.” The Tappan Zee.
In Vermont Jefferson was delighted to find sugar maple trees growing “in vast abundance.” He and Rush had been exploring the idea of replacing cane sugar, imported from the slave-owning West Indies, with what Rush liked to call “innocent maple sugar.” Since at least 1788 Rush had been arguing that maple sugar was preferable in every way to cane sugar, and Jefferson had become an enthusiastic supporter of his efforts. Before Jefferson left Philadelphia for his New England trip, he and Rush had sat over cups of coffee sweetened with maple sugar and discussed the possibilities. Jefferson, a slave owner, was interested in maple sugar’s promise for increasing the agricultural self-reliance of the United States. Now, in early June 1791, as Jefferson and Madison surveyed a Vermont hillside covered with the trees, the scheme seemed within reach, even as Rush in Philadelphia worked on revisions to his sugar-maple pamphlet, which he would present to the American Philosophical Society in August.
When Jefferson and Madison turned south again, they traveled down the Connecticut River, coming out into Long Island Sound between the villages of Old Lyme and Old Saybrook before traveling the length of Long Island to New York City. They paused at the village of Flushing (in today’s Queens) long enough for Jefferson to purchase the entire stock of sugar maples from the Prince family’s nursery there.
IN MAY 1791, just as Jefferson and Madison were about to leave on their New England trip, Hosack submitted a dissertation on cholera to the University of Pennsylvania medical faculty. He opened the work with a martial tribute to the stomach. “This organ, in a natural and healthy state, like a faithful well-armed Sentinel, is always on the watch, who when attacked, either repels the enemy, or deprives him of his arms, without which he is now incapable of defence.” Hosack dedicated his dissertation to his former teacher Bayley, a man who knew something about being attacked. It would be another sixty years before the London doctor John Snow would discover that cholera was a waterborne illness, and ninety years before the German scientist Robert Koch would isolate the cholera bacillus. Hosack’s analysis of cholera was firmly rooted in the humoral understanding of the body, yet his bold criticism of theories advanced by his famous new mentor, Rush, suggests how comfortable their relationship was—and how confident Hosack was growing in his own ideas.
His degree complete, he married a young woman he had met in Princeton, Catherine Warner, whom he called Kitty. They moved to Alexandria, Virginia, close to where the nation’s permanent capital city was being built. While Hosack worked at establishing a medical practice, Kitty bore their first child, a boy they named Alexander, after Hosack’s father. Soon, however, it became clear that the new capital was emerging at a glacial pace, and although Hosack was attracting some patients, he worried about supporting Kitty and Alexander. After agonizing deliberation, he concluded that both his professional prospects and his clinical skills would benefit from the most advanced and prestigious medical education in the Western world. The American professors whom he admired had all studied at the University of Edinburgh, a city that in the second half of the eightee
nth century was home to some of Europe’s most brilliant philosophers, naturalists, writers, and medical men. It was the heart of the Scottish Enlightenment.
Hosack found it “painful to think of leaving” Kitty and Alexander, but in the late summer of 1792 he settled them with his parents on William Street in New York and boarded a ship bound for Britain. It must have been a disorienting way to mark his twenty-third birthday that August 31—surrounded by strangers on the open Atlantic. When he disembarked at Liverpool, his first stop on the way to Edinburgh, a family friend treated him to an unforgettable evening. Hosack found himself sipping hot toddy by a cozy fire as a young Scotsman named Robert Burns sang odes to the beautiful land where Hosack’s own father had been born. He couldn’t have dreamed up a more romantic prelude to his new adventure. When he finally arrived in Edinburgh, he was dazzled by the turreted city—“that dream in masonry and living rock,” Robert Louis Stevenson would later call it. At one end of the Old Town sat Holyrood Palace, while at the other end Edinburgh Castle perched like a galleon atop the billowing cliffs. To the north was the neoclassical New Town, laid out by city elders in the middle of the eighteenth century, where fine masonry-work façades lined green squares.
At the university Hosack signed up for a punishing regimen. He attended classes twelve hours a day, racing from anatomy to midwifery, from pharmacology to chemistry, from clinical observation to dissection. Arsenic sizzled on red-glowing copper. Blade scraped on bone. In the evenings he shadowed the city’s surgeons as they walked the wards of the Royal Infirmary. Through it all, he soaked up the accumulated knowledge of centuries of medical instruction and practice. The animating spirit of the faculty was William Cullen, a professor who had died two years earlier but still practically ran the place from his grave, so great was his intellectual influence. Nearly everything Hosack learned about medicine that year—and a good deal of what he had already learned in the United States—traced its roots to Cullen in one way or another. After joining the Edinburgh faculty in 1755, Cullen had taught thousands of future European and American doctors his novel understanding of the origins of disease, which he saw as lying in what he called “spasms” of the nervous system. Cullen—whose nickname among the students was reportedly “Old Spasm”—had also upended the way materia medica (soon to be called pharmacology) was taught. The handbook that became Hosack’s constant companion, the Edinburgh New Dispensatory, owed its novel structure to one of Cullen’s insights.
For centuries before Cullen, reference books on the materia medica had listed all the known medicinal substances in alphabetical order within the huge categories of animal, vegetable, and mineral. It was a confusing system for a doctor trying to find a remedy for a particular ailment, and Cullen had pointed out that it made much more sense to organize medicines by their effects on the body—emetics, sudorifics, purgatives, and so on. By the time Hosack arrived in Edinburgh, the current edition of the Edinburgh New Dispensatory partly followed this revolutionary scheme, and for generations to come most new pharmacology textbooks would follow it, too. For this insight and so many others, Benjamin Rush, who had studied with Cullen at Edinburgh in the 1760s, wrote after the latter’s death in 1790 that “while Astronomy claims a Newton, and Electricity a Franklin, Medicine has been equally honoured by having employed the genius of a Cullen.”
In addition to teaching Rush, Cullen had trained many of the Edinburgh professors in whose classrooms Hosack now sat trying to absorb every new bit of knowledge. He studied the way they classified fevers, their most recent breakthroughs in chemistry, and how they prepared pills, infusions, tinctures, syrups, and every other form of medicine. As he listened to his professors, Hosack took notes not only about the content of their lectures but also about their oratorical styles. He did the same when he sat in church on Sundays listening to the Presbyterian minister. Should he ever find himself in front of a classroom filled with captive young men, he planned to avoid boring them. Hosack’s close relationship with Rush brought him to the attention of his Edinburgh professors, and he wrote to ask how Rush would feel about having some of his recent writings published in a British edition. There was strong interest, he noted, in Rush’s pamphlet on maple sugar.
Hosack missed Kitty and Alexander, yet for a young man like him—prodigiously energetic and hungry to learn—these were exhilarating months. One of his favorite classes was midwifery, a specialty practiced by male doctors as well as by female midwives and “man-midwives.” By an odd coincidence, Hosack’s midwifery professor was named Alexander Hamilton, although he looked nothing like his elegant American counterpart. Professor Hamilton had a stocky body, a jutting chin, and a squashed nose. He turned out to be a generous, sociable man, and he invited his new American student home to family dinners. Professor Hamilton also enjoyed hosting students and colleagues at a garden he kept on the outskirts of Edinburgh, including Hosack on at least one occasion. As Hosack strolled through the garden listening to the casually erudite conversation around him, he began to panic. Botanical expertise, it seemed, flowed in British veins. He normally felt at ease in the most exacting company, but now he was the odd man out, the uncultivated American. Standing there tongue-tied before Professor Hamilton and his guests, Hosack felt, as he later put it, “very much mortified by my ignorance of botany.”
Eighteenth-century Britain was a land obsessed with plants—growing them, collecting them, studying them, admiring them. The whole kingdom was covered in gardens. There were grand palace gardens, tidy public gardens in the cities, beautifully landscaped gardens around country homes, and countless little flower and vegetable gardens. For Professor Hamilton and his colleagues, though, it was the curative properties of plants that were most fascinating, because the vast majority of medicines known in the eighteenth century, as in every century before, had been ferreted out of bark, roots, stems, leaves, seeds, petals, and fruits. The leaves of mugwort (Artemisia vulgaris), for example, a member of the daisy family that dotted the lanes and fields of England, could be boiled into a medicinal tea believed to reduce menstrual bleeding. An infusion from leaves of menyanthes (Menyanthes trifoliata), a flowering plant known more commonly as bogbean, soothed herpes sores. The resin of arborvitae trees (Thuja occidentalis) produced an excellent cough syrup that was thought to have prevented scurvy in the British army at Boston during the American Revolution.
Edinburgh New Dispensatory, 1791 edition
The study of how to use plants to make medicine was called medical botany. It was an ancient field, yet almost two millennia after the Greek physicians Theophrastus, Dioscorides, and Galen had written influential treatises, Western doctors were still struggling to determine which plants alleviated which illnesses—and how they did so. Today, scientists know that plants produce four main kinds of antimicrobial substances, but in the late eighteenth century, these compounds were as little known as the role of microbes themselves. Doctors and botanists did their best with the tools they had, reading through thousands of plant descriptions in ancient, medieval, Renaissance, and contemporary texts in search of the keys that would reveal what made a given species medically potent. In both Europe and the United States, physicians fretted over the scarcity and expense of imported drugs like Peruvian bark, and they worked hard to find comparable native species. They traded case notes with one another and argued over medicines, dosages, and side effects. They conducted autopsies on patients whom their remedies could not save—or killed outright—and published the results, in the hope of nudging medical knowledge along the path of progress. Sometimes they left their desks, libraries, and surgical theaters to study under the open sky in botanical gardens.
Europe’s botanical gardens had originated in medieval medicinal gardens attached to monasteries. During the Renaissance the study of plants had gradually shifted from monasteries to universities, and botanical gardens were established in the sixteenth and seventeenth centuries in university towns such as Pisa, Padua, Leiden, and Oxford. In the age of European colonial expansion,
botanical gardens were becoming increasingly important to imperial powers eager to hoard and cultivate lucrative plant species such as cacao, coffee, and spices. For doctors and professors, botanical gardens served as encyclopedias, laboratories, and classrooms. They lugged their materia medica books to the gardens and compared written descriptions of plants to living specimens. They dug up roots to slice them into sheer slivers and examine them under microscopes. They boiled leaves in distilled water and mixed the resulting liquid with ammonia, sulphuric acid, and other chemicals to try to determine their composition. They pinched off flower petals and ground them to a pulpy mess with their mortars and pestles, making medicinal teas and salves that they tested on themselves and their patients.
Hosack had learned about the importance of plant-based medicines during his medical studies in New York and Philadelphia, but he had thought of them as supplies to be purchased from druggists and apothecaries. It wasn’t until he embarrassed himself in Professor Hamilton’s garden that he glimpsed a world in which garden rakes could unlock the saving power of nature. Then and there, he resolved to learn everything he could about plants. The best place in Edinburgh to do so was the botanical garden across the bridge from the university. It had started life as a small medicinal garden run by two local physicians near Holyrood Palace, but by the time Hosack arrived it had moved to a larger site on Leith Walk, where a professor of botany from the university lived in a beautiful “Botanic Cottage” surrounded by thickly planted herbs, flowers, shrubs, and trees. Medical students from the university paced the garden paths trying to memorize species names as their professors lectured about the ailments they thought (not always correctly) treatable by medicines made from these plants. Although Hosack left no record of visiting it, his newfound interest in botany must have led him to Edinburgh’s famous botanical garden from time to time.
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