Lewis and Clark left St. Louis under the influence of European ideas and mythologies about nature; these had captured the imagination of Thomas Jefferson. The primary nature belief in eighteenth-century European civilization was the classic balance-of-nature myth, which includes the following ideas: Nature, undisturbed by human influences, is constant over time and symmetric in space; there is a great chain of being, with a place for every creature, and every creature in its place, each performing a designed function; nature was designed and, if allowed to follow that design, functions perfectly, independent of human actions.
Constancy of nature was believed desirable and good -– the best possible condition for all life. Geographic symmetry was believed necessary, desirable, and beautiful. In the seventeenth century Godfrey Goodman, bishop of Gloucester, wrote that "the mighest mountains...carrie some proportion to the lowest bottome at Sea...that God might observe some kind of proportion,” echoing ideas of the Greeks and Romans about the necessity that nature be symmetric. But this was not the real North America, as Lewis and Clark were soon to discover.
The idea of nature’s symmetry manifested itself in several ways in the planning of the Lewis and Clark expedition. Most important, Jefferson believed - as was the common belief of his time - that the western mountains of North America must be symmetric with the Appalachians. Therefore, they would have the same width and height. This was important for Jefferson’s plan to search for a water route to the Pacific. It led to the belief that the western mountains could be crossed in a day or so, without great difficulty, and therefore an inland passage would be provided by the Missouri and Columbia rivers. This was believed to be not only possible, but necessarily true. The western mountains were "passable by Horse, Foot or Wagon in less than half a day," according to a late-eighteenth-century treatise promoting settlement of the West. One of the best maps of the late eighteenth century, by Aaron Arrowsmith - a map used by Lewis and Clark - said that the western mountains were "3520 Feet High above the Level of their Base." It is intriguing that one of the best map makers of the time took this belief to the point of providing precise, but totally wrong, numbers.
A mentor of young Thomas Jefferson, Reverend Maury, wrote that the western rivers that flowed into the Pacific should reach as far east as the Missouri reached west - once again an expression of a necessary symmetry - and the two rivers would be separated by "a short and easy communication." Jefferson instructed Lewis to follow the Missouri River to its source, then cross the mountains and follow the Columbia River to the ocean. He did not suggest a more open-ended goal of finding the most practical route to the Pacific, because nature’s symmetry had already dictated what that would be.
If the asymmetry of the mountains of North America had been known to Jefferson, or considered a likely possibility, the planning for the Lewis and Clark expedition might have been much different. First, Jefferson might have posed the goal differently: Seek the best water route to the Pacific. Second, he might have realized that a small party of men was unlikely to succeed in this endeavor, and he might have held off until the United States could, and was motivated to, fund a much larger military expedition.
Lewis was similarly educated and influenced by the predominant eighteenth- century belief in the balance of nature. But like Jefferson, he was also fascinated by natural history observations and by the potential of the recently developed scientific process. Thus he was, at least potentially, open to observations that might revise his ideas.
As experienced outdoorsmen, Lewis and Clark began their journey aware of the necessity to observe one’s surroundings carefully if one hoped to survive in the wild.
But once on their way, they encountered an environment very different from the European perception. They faced two environmental challenges: the first to overcome the influence of dominant, but inappropriate, European ideas about nature; the second to survive the heavy challenges of climate, topography, and wildlife largely unknown to Western civilization.
Ironically, although we have progressed greatly in our technologies and many other sciences, our approach to the sciences of the environment lags and remains heavily influenced by the idea of the balance of nature. Two resulting ironies of our modern information age are: first, that we rarely measure what we need to know, and second that if we do measure it, we seldom use the information. We would do better to follow the approaches of Lewis and Clark. Confronted as we will see throughout this book -- with the realities of nature in the New World, they observed, deduced, and responded in ways that were appropriate to what they experienced, although this required that they abandon the beliefs that formed the background of their European- based culture. In this way, their journey takes on a new and broad importance for us, beyond the fascination and excitement of the story of their expedition and beyond the confines of what we have come to call environmentalism.