Preface to the 2022 Edition of
The Planet-Girded Suns
by Sylvia Engdahl
Why Does History Matter?
This book is about history, the history of an idea that has been far more prevalent during the past five hundred years than most people realize: the idea that the planets of distant stars are inhabited. I am not referring to speculation about visitors to our world, either ancient ones or recent UFOs—both concepts that arose during the twentieth century and are not accepted by orthodox science. On the contrary, that travel between worlds might ever be possible did not even occur to the scientists, clergymen, and other intellectuals of the late seventeenth through nineteenth centuries who firmly believed that the planets of other suns must have inhabitants. Most argued that God would not have created a world of no use to anyone, but even those who did not put it in religious terms felt that it would be against nature for ours alone to be populated.
Serious opposition to that assumption did not arise until the mid-nineteenth century, and except for a short period in the early twentieth, the belief that there must be many inhabited worlds prevailed. This is not to say, of course, that society at large was aware of the issue or even that stars might be orbited by planets, since most people had too little education to have knowledge of astronomy. But the magazines, newspapers, and poems of the day, directed to the educated minority, made frequent reference to it, as did the writings of such diverse notables as Immanuel Kant, the Puritan minister Cotton Mather, and Benjamin Franklin. It was even included in a few eighteenth-century textbooks for children.
Why should we care today what our forebears believed? Now, the question of ET life is a matter for investigation by science. There are countless science books that deal with the issue. This book, originally published in 1974 and updated in 2012 and 2016, contains short sections about the science, but they too are fast falling into the “history” category. Radio astronomers are attempting to detect signals form extraterrestrial civilizations, and more exoplanets are being discovered every day. If you are looking for current scientific information, this is not the place to find it.
What you will find is a perspective on the issue that shows public interest in extraterrestrials is no mere passing fad, a subject assumed (erroneously) to have originated in science fiction. It is a fundamental aspect of human thought. It's significant, I think, that people of past centuries were convinced that other inhabited worlds exist, without any scientific evidence whatsoever. This historical fact reveals that human beings have an instinctive sense of kinship with the wider universe and a desire to see the realms that lie beyond this one small planet—and perhaps, eventually, to go there. Our ancestors conceived of such voyages only in a spiritual sense, as occurring after death. But we who have taken our first small steps into space are aware that our descendants may set foot on the worlds of other suns, and those of us who have faith in such a future believe it to be the destiny toward which humankind has been moving throughout history—a step essential to the long-term survival of humankind. Had this been known to the writers of earlier times who spoke of those worlds with longing, they would wonder at the public apathy toward space travel that prevails just when we stand on the threshold of fulfilling their dream.
And yet, today’s apparent apathy may be rooted in something much deeper than is commonly supposed. While updating this book for republication, I was struck by a parallel I had not seen before between our time and an earlier era, which puts my worries about our lagging progress in space into a different light. And so, as stated in the 2012 Preface, I added an Afterword to the book, which has since appeared in The Space Review and in my ebook From This Green Earth: Essays on Looking Outward. It argues that when a new concept of the universe arises, it provokes unconscious anxiety in the public that takes time to fade. Just as in the seventeenth century people were upset by the knowledge that the stars are suns scattered in space rather than lights fixed to a nearby sphere, the growing awareness that Earth is not safely isolated from whatever lies beyond makes many of our contemporaries uneasy. Thus the predominant feelings about spaceships are ambivalent. Nevertheless, if an impulse toward belief that we are not alone in the universe is indeed an innate characteristic of human beings, as our history suggests, we can be sure that those who follow us will not turn back from becoming spacefarers.
Foreword to
The Planet-Girded Suns
Our Forebears' Firm Belief in Inhabited Exoplanets
Surprising though the current interest of scientists in the possibility of life in other solar systems is to some, a still greater surprise to most people of today is the fact that belief in inhabited extrasolar worlds is not new. The idea was not, as is commonly believed, invented by science fiction writers. On the contrary, it was accepted by the majority of educated people from the late seventeenth century until the early twentieth century. Scientists, philosophers, clergymen and poets wrote a great deal about it. When in the 1850s the head of a well-known college wrote a book suggesting that there might not be other inhabited worlds, he published it anonymously because he felt it might damage his reputation--and indeed, most of the book's many reviews were disapproving. A prominent university's magazine declared that plurality of worlds was a subject on which "until now it was supposed that there was scarcely room for a second opinion."
Cover of 2016 edition
This fact does not appear in history books. Until recently the information was to be found mainly in the books and magazines of past centuries. Famous authors of those eras sometimes mentioned their belief in other worlds, but they spoke of it briefly and casually, thinking it too commonplace an idea to merit much discussion. Most of the writers who went into detail about it are no longer famous. Their books, many of which were bestsellers in their time, have been nearly forgotten. They remain in the collections of large libraries, rarely called for, in some cases with bindings so old and brittle that they fall apart in one's hands when one first opens them to read.
The speculations in old books, and in most modern scientific ones, have nothing to do with UFOs. The question of whether there are inhabited worlds elsewhere in the universe is separate from the question of whether or not any of those worlds' inhabitants have ever visited our world. Nonfiction of past centuries about extrasolar planets does not mention such a possibility. The idea did not occur to anyone until about the time of World War II. Since then, many people--some of whom are scientists--have investigated records of strange objects seen in the past, and have suggested that these might have involved alien visitors. But science considers the existence of other civilizations far more probable than the notion of their representatives' having come here. And during the former period when almost all educated people were utterly convinced that superior civilizations exist, actual contact between the ones of different solar systems was not even imagined.
At the time this book was written, searching for the old writings about extrasolar worlds was a little like a treasure hunt: one could not predict just where they would be found, and one had to look in many places without finding anything. Libraries had reference tools that helped, but these tools were only a beginning; often they provided merely clues leading on to other clues. Occasionally they led to a dead end, such as a work of which the only existing copy was in an inaccessible museum. (Thanks to the progress of technology since the 1970s, some of the books then only in exceptionally large university libraries are now available on the Internet as scanned ebooks.) Yet an astonishing number of relevant volumes were available, even before scholars had published the accounts of past writings that now exist. One could go to a library shelf, take down a magazine well over a hundred years old, and turn to an article that thousands of people must have read when it was new--and that never, perhaps, has been looked on by anyone now alive. The wording of such articles may seem quaint, and their authors may have been ignorant of facts that are now known, but the idea expressed is often closer to what scientists are saying today than to what they said when one's grandparents were young.
There are many current science books about extraterrestrial life. This, however, is not a science book. It is the history of an idea. Not all men and women with important ideas are scientists; science studies only that which can be systematically observed. Long before the invention of the telescope made it possible to observe distant parts of the universe--long before the belief in other worlds became popular--there were men who thought about what might lie beyond Earth. Some had followers, but others were ridiculed or persecuted and at least one was put to death for his theories. Since that time more facts about the universe have been learned; present views of far-off solar systems have scientific foundation. Still, the question of what inhabitants of those solar systems are actually like cannot yet be studied scientifically. When scientists give opinions on it, they are speaking not as authorities but simply as members of the human race, just as their predecessors did. They are expressing not proven truths, but thoughts. This book is the story of humankind's thoughts about the worlds of other suns: past thoughts, remarkably similar present thoughts, and thoughts that will be investigated in the future.
Thoughts about the unknown concern not only science, but religion. For many centuries all speculation about astronomy was inseparable from religion, since the mysteries of the heavens could be explained only in religious terms. Today, when more scientific data can be obtained, there seems to be a firm line between the two. In the past, however, people who drew a line between religion and other affairs placed the subject of other worlds on the "religious" side of that line, while it now usually falls on the "scientific" side. Unlike their predecessors, modern scientists who believe that the universe was created by God do not spend their time debating about whether the various features of it could have resulted from what they think God must have done; they accept their observations as evidence of what God did do. In other words, they study what exists and form their theories from its nature--not God's, which they do not expect to explain scientifically.
To people of past eras such reasoning would have seemed backwards. They felt that they knew a great deal about God, and they realized how little knowledge they had of the universe. At first they did not guess that it was possible to obtain more. Gradually, as science did acquire more knowledge, certain ideas about God had to be discarded; and although some lost faith in all religion when that happened, others came to feel that less had been known of God than had been supposed. They developed new ideas about religion as well as about astronomy, sometimes disagreeing strongly with the established churches. But until the twentieth century, few if any people separated their personal religious beliefs from their thoughts about what the universe is like. Even those who paid little attention to religion in everyday life considered cosmology--the nature of the cosmos--too unknowable to be viewed as a purely scientific matter.
Near the end of the nineteenth century another crisis occurred, one that has not been discussed often. People had been saying for two hundred years that a world would not be created for no purpose, and the only purpose anyone could think of was habitation. Travel from one world to another was not thought possible. So when scientists concluded that the moon and nearby planets are not inhabited, it was natural to start wondering whether the universe is really purposeful. The most common argument for extrasolar life seemed less convincing than before. Furthermore, around the turn of the twentieth century a new theory was adopted about the origin of planets. Astronomers began to think that solar systems came into existence accidentally. Such accidents were considered rare; even among people who still viewed cosmology in a religious way, there were many who abandoned their faith in worlds of other suns.
Today, the opposite situation prevails. Since the mid-twentieth century scientists have believed it is highly unlikely that ours is the only inhabited planet in the cosmos, for solar systems have been considered common--a theory recently confirmed by the discovery of many planets orbiting other stars. The likelihood of sentient species elsewhere is accepted by men and women of differing faiths, and also by those with no religious faith. It is frequently assumed that discovery of extraterrestrial life would be upsetting to religion. This is not true; there has been little if any conflict since the early seventeenth century and most if not all the religious thinkers who have considered the issue believe that existence of other inhabited worlds is compatible with their faith. (Interestingly, a poll has shown that many people think members of other religions would be disturbed, though not their own.) Yet the former Soviet Union's philosophy of dialectical materialism supports the same idea. In 1958 a Soviet astronomer wrote, "The thesis of the existence of life outside the earth is shared in our epoch . . . in equal measure both by the materialists and by the idealists." There are few issues of such importance on which people with conflicting philosophies can so readily agree.
If life does exist in other solar systems, our view of it is surely important. This book tells the story of humankind's view.
Copyright 1974, 2012, 2022 by Sylvia Engdahl