Alfred Wallace: Spiritualism, intelligent evolution, and natural theology

Alfred Wallace: Spiritualism, intelligent evolution, and natural theology

Wallace is recognised alongside Darwin as the co-discover of natural selection, the mechanism that makes evolution possible. Wallace was eventually to reject his own discovery in relation to the evolution of humans while retaining his belief in it for the rest of nature. For Wallace accounts of evolution were incomplete without a spiritual dimension. The reason for this turn-around was that in the decade or so that passed between natural selection being presented to the world when Wallace and Darwin’s papers were read to the Linnean society in 1858, Wallace had begun to investigate spiritualism, and become convinced of the existence of many genuine demonstrations of contact with a world of spirit.

His experiences gave him a totally different perspective to most naturalists at the time, who were either atheists who rejected God altogether, or were creationists who believed in the creative role of a deity but lacked any good explanation of how this deity interacted with the physical world. Wallace reconstructed a view of nature in line with the traditional medieval cosmos – a hierarchy of spiritual beings issuing forth from a Supreme Mind, which played a directive role in human evolution, and could interact with humans under certain circumstances.

Interestingly Wallace’s conversion to spiritualism did not occur while immersed in the cultures of the Amazon and South East Asia in which such beliefs were already accepted and pervasive. He only became convinced when able to carefully control the conditions of séances within his own home and other settings where he believed he could prove their authenticity.

Ultimately Wallace’s knowledge of biology and spiritualism combined to make him a believer in an intelligent creative mind, an afterlife, and evolution towards perfection. Although Wallace never accepted the authority of a redemptive God-in-man and so could not be considered a Christian, the universe he described was entirely compatible with the Christian universe, the great chain of being, and the hierarchy of spirits and angels governed by an overseeing deity. For Wallace, the journey away from religion into naturalism eventually came full circle, and he arrived once more at the spiritual cosmos that he had initially tried to break away from.

Early life

For long periods of his life Wallace was first and foremost an explorer and collector of specimens from the world’s tropical wildernesses. Although one of the leading scientists of the day with over one thousand published scientific papers, the role he played for the public was more like that of David Attenborough, and his two best known works were travel books for the general public. But unlike today’s equivalents, he usually journeyed alone with just his backpack and canoe, or accompanied by local guides from the indigenous population, and spent years at a time in his chosen locations.

To say he had frequent brushes with death is not an exaggeration. He many times became seriously ill while travelling in the Amazon and South East Asia. In Brazil he survived being stung fifty times by a swarm of wasps, nearly had his canoe capsized by a crocodile, and was within inches of death when a gunshot passed so close between his arm and chest that it broke the skin. In Malay he wended his way through tribes of head hunters and pirates who regularly attacked ships or sailors on shore.

In fact Wallace had lived a rather charmed life from an early age, having survived a bout of scarlet fever which according to his family left him “within hours of death,” he would have drowned in the river Beane as a young boy but for his brother rescuing him, and a few years later nearly died in an icy pothole before another rescue. From a young age Wallace spent much time reading and the volumes of Victorian fiction, the classics, and poetry may well have been where he first derived his love of adventure.

Leaving school at fourteen and initially trying his hand at factory work, he found more satisfying employment with his brother as a freelance surveyor, travelling the UK working outdoors, lodging in farms, or on larger expeditions scaling cliffs and ravines and falling asleep by firelight in the Welsh limestone caverns, while following his private reading lists. While staying at Bryn-Coch farm in the Valley io Neath, his brother left for a series of meetings, leaving Alfred with little to do. It was here that he chanced upon a short paperback on botany, published by the Society for the Diffusion of Knowledge, but quickly progressed to much more comprehensive works by Lindley and Loudon, before arriving at Darwin’s Journal of the Voyage of the Beagle.

Above: Collegiate School, Leicester. It was here that Wallace became interested in psychical phenomena, and after studying the methods of Spencer Hall, he found he could mesmerise the pupils. He was to repeat this feat on the Amazonian Indians, which they accepted quite naturally, and believed Wallace to be a white medicine man. The presence of universal faculties like mesmerism in humans which he felt were quite useless for survival was to influence his views on spiritual evolution and the derivation of the human mind from the mind of God.

Now twenty-one and having discovered a teaching vacancy, he applied for the job, taking along some sketches and maps he had made of Neath to the interview. In a freer age, this was enough to convince the headmaster he had suitable skills, and he accepted the job as a teacher. Having attended a few lectures by Spencer Hall on mesmerism, Wallace found that he could perform it on boys in the school by following the same techniques. “On the rigid outstretched arm I would hang on the wrist an ordinary bedroom chair, and the boy would hold it there for several minutes, while I sat down and wrote a short letter.” When the headmaster was informed of this, he invited friends to watch the displays.

A year later Wallace was back surveying, spending extended trips of several days in the remote regions of Wales with his brother. Around this time he read and was fascinated by Robert Chambers’ Vestiges of the Natural History of Creation, a huge compendium of natural history which described the transmutation of species, but made no offering as to the mechanism by which species changed. He resolved to use the money he had manged to save while surveying, a sum of around a hundred pounds, to pay for a ticket to South America and some equipment to attempt a career as a collector of species, and to search for evidence of evolution.


Wallace was twenty-five when he sailed from Liverpool on the Mischief in April 1848 with his friend and fellow collector Henry Bates. They arrived at Salinas on the coast of Brazil thirty days later. They were joined by another collector named Richard Spruce and Wallace’s cousin. Initially staying close to civilisation they were able to sustain themselves and fund further adventuring by sending specimens home for a twenty percent commission agreed with an agent in London.

After a year or so the group of collectors had separated, and Wallace set off exploring the Rio Negro area of the Amazon in Central and Northern Brazil and Venezuela, alone in his canoe or with local Indian guides when needed:

“they would tell me forest tales of jaguars and pumas, and of the fierce wild hogs, and of the dreadful curupuria, the demon of the woods, and of the wild man with a long tail, found far in the centre of the forest” (Travels on the Amazon and River Negro)

Stories such as these led him further into the Amazon, into an area so deserted it was known as the “dead river”. On one journey a crocodile tried to capsize the canoe from beneath, and on the way back a gun in the bottom of the canoe went off, grazing his arm and chest, leaving a wound that took several weeks to heal. He was at one point abandoned by his Indian guides altogether, who left in the night growing increasingly uneasy about travelling through the lands of foreign tribes. Richard Spruce, he was to learn later, narrowly escaped with his life under similar circumstances in the same area. Initially Wallace followed the trail of a select group of great European explorers – Humboldt, Bonpland, Natterer – and finally crossed into territories he was satisfied he was the first European to lay eyes on. Finally weakened by successive bouts of yellow fever having spent three years in remote parts of the Amazon, Wallace retraced his route to the coast, and boarded the Helen bound for England.

Even the journey back was wrought with danger. The Helen caught fire and burned throughout the night, destroying all of Wallace’s specimens. They escaped to the coast of Bermuda on two small life boats, and from there caught a rather unseaworthy tug, which eventually made it back to England. Wallace published two books on return, one of them self-published with a run size of 250 copies which about broke even, and another profit share venture with a publisher, that did not return any profit for nine years.

Above: Locals remove a python from Wallace’s hut, as related in The Malay Archipelago. It was from a hut similar to this that Wallace penned his papers on natural selection, which along with Darwin’s work comprised the Darwin-Wallace theory of evolution, one of science’s most influential ideas.

Having recovered his financial position following a £200 insurance payment for his lost specimens, and inspired by the writings of Ida Laura Pfeiffer, Wallace’s chose the Malay Archipelago as the destination for his next adventure. This was the island chain comprising modern day Papua New Guinea, Indonesia, and the Philippines. Wallace spent eight years in total exploring, collecting, and note taking. Though not as dramatic as his Amazonian trip he relates in his journals of sleeping in the huts of Indians by the Sarawak River with smoke-dried human skulls suspended from the ceiling, of human sacrifice in the Sunda Isles, and pirates off the coast of Papua New Guinea.

Around this time ideas surrounding the long illusive mechanism of evolution were swirling in Wallace’s mind, and he wrote a series of papers on the subject. The first, written in Sarawak in Borneo, became known as the Sarawak paper. It laid down a challenge to the influential naturalist Charles Lyell’s assumption that species were immutable. Lyell informed Darwin of the paper, and although Lyell was impressed, Darwin dismissed it as a form of creationism. There followed another paper written from the Celebes. At this stage even Wallace did not seem fully aware of the significance of his ideas.

It was not until ill with Malaria on the small island of Ternate that the importance of the mechanism of evolution seemed to fully emerge from his subconscious. Wrapped in blankets despite a temperature over 30 degrees in the cabin, and vividly aware of the struggle life can involve, the process by which species change from one form to another suddenly flashed before him with great certainty. As he relates in his autobiography:

“as animals usually breed much more rapidly than mankind, the destruction every year… must be enormous in order to keep down the numbers of each species, since they evidently do not increase regularly form year to year, as otherwise the world would long ago have been densely crowded with those that breed most quickly. Vaguely thinking over the enormous and constant destruction which this implied, it occurred to me to ask the question, Why do some die and some live? And the answer was clearly, that on the whole the best fitted live. From the effects of disease the most healthy escaped; from enemies, the strongest, the swiftest, or the most cunning; from famine, the best hunters or those with the best digestion; and so on. Then it suddenly flashed upon me that this self-acting process would necessarily improve the race, because in every generation the inferior would inevitably be killed off and the superior would remain – that is, the fittest would survive… The more I thought over it the more I became convinced that I had at length found the long-sought-for law of nature that solved the problem of the origin of species.” (Wallace, My Life, 1908)

He considered this his “great moment of illumination.” In contrast to Darwin, who had seen the process for himself with equal clarity twenty years ago but never published, Wallace wasted no time and immediately began to share the idea – with Lyell, Hooker, and Darwin himself! Darwin now saw clearly that Wallace had now found exactly the same path that he had walked alone for the past twenty years and even used similar phrasing, and in contrast to the cautious Darwin, the young explorer in Malay seemed to have no intentions of keeping his ideas to himself.

Keen to protect the interests of their friend Darwin, while also acknowledging the originality of Wallace’s contribution, Lyell and Hooker arranged for Wallace’s paper to be read to the Linnean Society on the 1st of July 1858. They did not seek Wallace’s consent to read his paper to the society, believing consent already implied by his seeking Lyell’s opinion (and refereeship), and doing so would have taken at least 6 months.

Consequently, back in Malay, Wallace was oblivious to the history that was being made and his role in it, and had returned to the daily trials of the adventuring collector, enduring a particularly difficult expedition to the Dorey area of New Guinea. This was perhaps the most difficult of his trips while in Malay. Torrential rains fell, ants swarmed the entire cabin, carrying away specimens, tearing out insects he had gummed to boards and carrying them off before his eyes. Returning from this expedition to the less remote base of Gilolo, he received the letter informing him of his theory’s reception by Lyell, Hooker and Darwin, and publication to the society.

Above: A contemporary edition of The Malay Archipelago. This book, along with Miracles and Modern Spiritualism, still make excellent reading.

Darwin quickly followed through with the publication of On the Origin of Species and consulted with Wallace over the manuscript. Wallace remained hugely impressed with the book for the rest of his life, to such an extent that he never wrote his own book on the mechanism of natural selection, feeling that Darwin had done a better job than he could. It may also be that Wallace did not feel like writing the arduous and exhaustive account the theory demanded, as he said in a letter to Bates, “I feel really thankful that it has not been left to me to give the theory to the world.” Wallace decided instead to turn his notes from his eight years in the South East Asia into The Malay Archipelago, a vast two volume account of his time there written in a light style, it was to become one of the great Victorian travel books.


Wallace was one of the first two minds in history to perceive the profundity and significance of natural selection, but he was soon to reject the principle with similar conviction with regard to human evolution. His investigation of spiritualism was an important reason for the revision. Wallace’s approach to spiritualism was no different to his approach to other subjects he investigated: he approached it with an open mind, and formed a view based on evidence. He came to believe that spiritualism should become a new branch of anthropology, something which would become true in the second half of the twentieth century, which the rise of publications like Anthropology of Consciousness, the Journal of Transpersonal Psychology, the Journal of the Society for Psychical Research, and the Journal of Parapsychology.

In the mid-eighteenth century professional fake mediums abounded. Some put on displays more like today’s magic shows or horror walks with masked actors – clearly fake experiences designed for entertainment purposes – others professed to be entirely genuine and deliberately deceived. A third, and probably large, category appeared to believe they had some real paranormal abilities but would also engage in fake performances to increase their income. Amongst the great variety of fakes, Wallace became convinced there also existed many real paranormal phenomena.

On 22nd July 1865, Wallace attended a séance at a friend’s house, in which he witnessed the typically reported knocking and movement of the table. Wallace was impressed, suspecting what he had experienced was genuine. He reproduced similar séances with mediums at his own home several times, witnessing the tapping, knocking, and table movement in response to questions, levitation, names appearing on blank paper, musical instruments producing spontaneous sound, and the appearance of fruit in bowls and flowers in vases. All of these were regular occurrences in 18th century mediumship. Wallace was more impressed with these events within his own home, where he was able to control the environment, and prevent tampering e.g. by attaching thin paper sheets to the table legs to prevent anyone present moving the table.

He also noted that a number of men of science, many of them initially doubtful, had come to similar conclusions including Michael Faraday and William Crookes, as well as other intelligent people who he knew to be honest. A medium called Mrs Marshall, using letters identified through knocking, spelled out the name and place of death of his dead brother, and was able to add the name of the last person to see him alive, at Wallace’s request. Spiritualism became a central part of the lives of Wallace, his wife and sister, and other family members.

He soon learned that the requirement of a darkened room for a séance was not in order to hide anything as many assumed, but was necessary to instil the required state of awareness and sensitivity in the medium. Likewise, he became aware that a slight disturbance would break the concentration of the medium sufficiently to instantly end the paranormal occurrences. He believed that this explained why mediumship often failed to produce results under the eye of overly critical or somewhat hostile observers, and this inevitably produced an obstacle for sceptics, who believed mediumship not standing up to a critical investigatory environment was evidence the whole field was fakery. Wallace quoted an interesting passage from Dr Frederick Willis, a Professor at the New York Medical College, in respect to this:

“One evening the medium went into the dark room alone, and took her seat at the piano. I was in the sitting-room adjoining (the door between was open), the light from which made every object in the circle-room distinctly visible. Scarcely had the medium struck the first note upon the piano, when the tambourine and the bells seemed to leap from the floor and join in unison. Carefully and noiselessly I stole into the room, and for several seconds it was my privilege to witness a rare and wonderful sight. I saw the bells and tambourine in motion. I saw the bells lifted as by invisible hands and chimed, each in its turn, accurately and beautifully with the piano. I saw the tambourine dexterously and scientifically manipulated with no mortal hand near it. But suddenly, by a slight turn of the head, the medium became aware of my presence; instantly, like the severing of the connection between a galvanic battery and its poles, everything ceased. Mark this; so long as my presence in the room was known only to the invisibles, so long the manifestations continued in perfection; the moment the medium became aware of it, everything stopped. A wave of mental emotion passed over her mind, which was in itself sufficient to stop the phenomena at once. The incident proved to my mind most clearly that, in most cases, it is the condition of the medium that renders it so difficult for spirits to perform these wonders in the light rather than any lack of power or disposition on their part.” (Quoted in Miracles and Modern Spiritualism)

Having spent two years investigating spiritualism under controlled conditions, and reading everything he could find on the subject, Wallace wrote a short book for private circulation called The Scientific Aspect of the Supernatural, and sent copies to scientific colleagues and friends. Even the book itself was to become a source of validation. His sister Frances relates:

“The book was written by my brother Alfred and with 24 others was laying on my table they had been there four days and I had not made time to give them away. One morning I had been sitting at my table writing, and left the room for a few minutes when I returned the paper parcel was opened and the books laying on chairs and tables in every direction – I immediately called my friend the medium and told her of it, we then said do write out what is the meaning of this, though I can guess, they are to be distributed and not lay here idle, Yes Yes 3 knocks, then was rapped out this sentence, ‘One for my sister Frances, I have marked it’ upon this I opened one of the books and looked through the leaves and soon found marks with red crayon which I had on my table. I then said if you could do this while the book was shut you could write my name on this book while it lays under my hand, in a few minutes I opened the book and found Frances Wallace written, now dear spirit write my marriage name, I shut the book and in two minutes opened it again and the second name written was Frances Simms”

Wallace soon came to believe that mediumship involved extreme powers of concentration that were easily disturbed. He believed that a hostile environment would prevent such concentration, and this explained why feats of mediumship demonstrated within his own home were not always replicable elsewhere. The same thing has been noted by contemporary parapsychology researchers.

For Wallace the most logical explanation for events such as these was that another order of beings existed in the universe, who had knowledge of our world and were capable of acting on it, and we could be put in touch with them by some among us who had unusual perceptive senses. The existence of spirits fitted not only with his observances in England but was congruent with the reports of a vast number of cultures from around the world and in all ages. Around this framework, Wallace shaped a new outlook on life, and a new casting of its purpose and meaning. As he summed up in an 1892 encyclopaedia entry:

"The universal teaching of modern spiritualism is that the world and the whole material universe exist for the purpose of developing spiritual beings – that death is simply a transition from material existence to the first grade of spirit-life – and that our happiness and the degree of our progress will be wholly dependent upon the use we have made of our faculties and opportunities here.”

This view of the universe as a school or development phase for growing spiritual beings remains extremely popular today, where it is most frequently expressed in New Age spirituality, but also continues to thrive in spiritualist churches.

Above: A spirit photo of Wallace and his mother: Such a photo could have been obtained by double negative exposure, though Wallace maintained that the photo was genuine as no such image of his mother had ever been taken to use in a fake.

In 1875 Wallace released the book On Miracles and Modern Spiritualism. It is a remarkable document in which he describes his experiences at séances, his means of investigation, and theoretical points regarding spiritualism, all in a similarly comprehensive style to his biological works. The reaction from colleagues varied tremendously. Many were positive. Robert Chambers, author of Vestiges of the Natural History of Creation, contacted Wallace stating “I have for many years known that these phenomena are real.” Chambers also stressed that the term “supernatural” was the cause of much confusion, and that such things should be considered as natural as anything else found in nature. Other notable figures within the scientific community resolutely refused to give the spiritualist ideas any credence and refused to attend séances following Wallace’s invite. G.H. Lewes collaborated with the editor of the Pall Mall Gazette to publish criticism of Wallace’s views on spiritualism, while blocking from publication Wallace’s attempts to reply.

Wallace believed that the resistance to spiritualism within British science was akin to the early resistance to mesmerism and hypnosis, which by then had been proven genuine beyond any doubt. More generally it resonated with the resistance to any great change in the outlook of science. From Miracles and Modern Spiritualism: “The whole history of science shows us that, whenever the educated and scientific men of any age have denied the facts of other investigators on a priori grounds of absurdity or impossibility, the deniers have always been wrong.”

When Wallace visited America on a speaking tour, he found that the American scientific community in general was less sceptical about mediumship than the British, and men of science were less likely to dismiss the claims without any investigation. Wallace met with William James, regarded by many as the father of modern psychology, on several occasions. James had a strong interest in religious experience of all kinds, and played a leading role in the foundation of the American Society for Psychical Research.

In America Wallace’s spiritualist encounters became more dramatic, and he reported the appearance of figures in séances who he was able to actually reach out and touch. One such séance was exposed as fraud when interrupted: actors were found in a secret compartment in a wall. While there has been suggestive confirmation of mental parapsychological phenomena in contemporary parapsychology research, there has never been any report of solid, touchable figures appearing in laboratory conditions.* It may have been that Wallace was at times taken in by fraudulent mediumship in America in his later years. Though by this time he had moved beyond the question of validity, having proven it to his satisfaction many years earlier. By now though Wallace was convinced that at least some aspects of mediumship were genuine, and had long since moved on to its philosophical implications as his main concern.

Spiritual beings and directed evolution

Having encountered what he believed to be overwhelming evidence for spiritualism, Wallace began to reframe his evolutionary ideas. He no longer felt that naturalistic causes could adequately explain the existence of humans. Unlike the rest of nature, the human mind was only partially formed by natural selection, its existence was also directed by an “overruling intelligence”. A few years after his moment of clarity on Ternate, Wallace had already rejected natural selection as the sole driver of evolution, and attempted to form a more comprehensive theory that integrated nature with spirit and deity.

Wallace noted universal human faculties in people around the world such as mathematics, music, art, dance, and humour which he believed played no role in their survival. He was convinced that these shared faculties were evidence of the existence of a shared mind, the mid of a deity, from which all human minds derived. If advanced capacities show up in all people that are not down to natural selection then a plausible explanation of why is that human minds have been conformed to a greater intelligence that exists independently of them. Human minds have derived from the same higher mind, and so shared features are present in all humans, even if those features do not give them an evolutionary advantage. In Christian terms, man was a made in the image of God.

Wallace’s now arrived at a description of life that was very similar to the Christian cosmos of the middle-ages: a great chain of beings stretching through the physical to the mental to the hierarchy of purely spiritual beings, all held in place by the first cause, God. Though the two remained friendly, Darwin was horrified with this turn in Wallace’s thinking, accusing him of “murdering your own and my child.” It was not the notion of God’s existence that horrified Darwin, for Darwin never rejected the possibility of a creator completely, it was the abandonment of natural selection as the sole driver of evolution in humans.

Above: Beetles from the Wallace Collection. For Wallace natural selection controlled the animal kingdom, but humans had traits that required a spiritual explanation.

Above: The cosmos Wallace discovered, through the synthesis of evolution and spiritualism, strongly echoed the great chain of being which had dominated earlier European thought from Platonism to Christianity. (Illustration of the great chain of being from Didacus Valades Rhetorica Christiana, 1579).

In 1896 Wallace received a prophecy from a spirit girl at a séance: “You will come more into the world, and do something public for spiritualism. The third chapter of your life, and your book, is to come.” If this prophecy came true, it was undoubtably with the writing of The World of Life. The book was a synthesis of fifty years of work on the theory of evolution with his own ideas on spiritual creative power. It represented the final intellectual position of Wallace’s long journey. Beginning with an exposition and defence of natural selection in relation to the animal kingdom, he then moved to a demonstration of why natural selection was insufficient in the case of humans, and then on to why the more traditional concepts of God and spirits were necessary.

He then attempted to solve what he viewed as the final problem – the synthesis of science and religion. He argued that the separation of science and religion came from the difficulty in reconciling the transcendent God and the physical world. This could be overcome by acknowledging the existence of a hierarchy of intermediary beings of spirit, who were observable to science through carefully controlled séances, and who had played a guiding role in evolution to ensure that human beings came into existence. He summed up in The World of Life:

“If, as I contend, we are forced to the assumption of an infinite God by the fact that our earth has developed life, and mind, and ourselves, it seems only logical to assume that the vast, infinite chasm between ourselves and the Deity is to some extent occupied by an almost infinite series of grades of beings, each successive grade having higher and higher powers in regard to the origination, the development, and the control of the universe.”

The typical religious answer to the question of creation is “God made it so”, with no further detail of how, which tends to be unsatisfying to the nonbeliever. Wallace believed we could now add details of ranks of intelligence between God and man and that séances had proved their existence. These messengers or spiritual agents have a formative influence over aspects of evolution. They also give insight into the ultimate meaning of life. The growth of each human being, begun on earth, will complete in the spirit world:

“In this world we have the maximum of diversity produced, with a potential capacity for individual educability, and inasmuch as every spirit has been derived from the Deity, only limited by the time at the disposal of each of us. In the spirit world death will not cut short the period of educational advancement. The best conditions and opportunities will be afforded for continuous progress to a higher status, while all the diversities produced here will lead to an infinite variety, charm, and use, that could probably have been brought about in no other way.”

The World of Life was a summary and integration of all of Wallace’s previous investigations, while Miracles and Modern Spiritualism went into more detail about his experiences, study, and investigation of spiritualism.

In the end Wallace was just as comfortable with the great public contemplators of life’s meaning such as Carlyle and Tennyson, with whom he formed friendships later in life, as he was with Darwin and Lyell. He never reconciled to a God-made-man atonement, but was also unable to see mankind as merely the highest being in the animal kingdom, and constructed a view of life essentially similar to the medieval Christian cosmos. Convinced our mental and moral nature could never have arisen from naturalistic forces and the process of natural selection, he instead posited that they arose from teleological agents, spiritual in nature. Although not a Christian, Wallace’s “Supreme Mind” had personal characteristics, and hence explained the most distinctly human characteristics of humankind.

* The current status of parapsychology seems to be that a number of parapsychological phenomena with statistically significant effects have been found, though there is often difficulty in replicating the studies, and no real agreement about the mechanism of these abilities. (This applies up to about 2013, I have not really followed the field much since then.) We should also note Wallace’s observations that critical conditions interfered with the sensitive state required to perform paranormal phenomena, and this may explain why some events, such as the appearance of figures, have never been convincingly demonstrated in laboratories.

Cover image: Evstafieff/Down House, Downe, Kent, UK/English Heritage Photo Library/Bridgeman