In January 1924, London's Strand Magazine published a detective story that contained this scathing assault on the idea of the living dead:
What have we to do with walking corpses who can only be held in their grave by stakes driven through their hearts? It's pure lunacy.
The world is big enough for us. No ghosts need apply.
At first glance, these lines appear to have little in common with sentiments expressed in a travel log released three years earlier:
Such séances have been going on now for 70 years, with innumerable witnesses of credit who will testify, as I have done here, that all fraud or mistake was out of the question.
Altogether I should think that not less than 20 spirits manifested.
The first example dismisses ghosts as mere figments of the mind, but the author of the second accepts their existence as indisputable fact.
Such discrepancy isn't especially surprising — until it becomes clear that both these passages were penned by the same author, the Scottish doctor and novelist Sir Arthur Conan Doyle.
"This is the man who created one of the most rational characters in literature — Sherlock Holmes," literary historian Susannah Fullerton said.
"[Doyle] became completely obsessed with spiritualism."
The spiritualist movement arose during the mid-1800s, promoting the view that the living could communicate with lost loved ones. Doyle drifted towards it during his mid-20s.
"Curiously enough, my first experiences in that direction were about the time Sherlock Holmes was being built up in my mind," he recalled in 1929.
"As I grow older, the psychic subject always grows in intensity."
That intensification coincided with several personal tragedies — Doyle's eldest son and only brother succumbed to Spanish flu about a year before he embarked on a voyage to Australia in 1920.
"He did have a desire to convert others — that was the whole reason behind the trip," said Ms Fullerton — who, while she doesn't at all share Doyle's views, has explored them in her book Brief Encounters.
"He went to séances. He even went over to New Zealand … [where] there was a medium, in Christchurch, who had a 'psychic' dog."
In his downtime down under, Doyle allowed himself more terrestrial pleasures. He held a possum at Humbug Scrub, near Adelaide, and the city earned his praise: "I have seen few such cities, so pretty, so orderly and so self-sufficing".
At the local art gallery he was impressed by HJ Johnstone's Evening Shadows, a painting of the River Murray that includes a depiction of Aboriginal Australians — whose treatment by wider society was described by Doyle as a "dark stain upon Australia".
He visited Perth and Brisbane, went to football and cricket matches in Melbourne, and took a Sydney Harbour cruise.
"For the first time, he saw people on surfboards, which he found intriguing," Ms Fullerton said.
"He was down in Melbourne at the time of the Melbourne Cup and he hated the gambling and the betting that went on."
Doyle faced 'hostile crowds' during crusade
Following its emergence in the 19th century, spiritualism enjoyed something of a second life in the early 20th, amid collective social shell shock.
"To a large extent it grew out of World War I — there was a sense that the world had just exploded, and the way of life that people were used to had been changed forever," Ms Fullerton said.
"Many people were missing relatives — sons, brothers, fiances and husbands. People clung to hope and thought, 'Well, maybe there is a chance we can speak to our dead son through a séance'.
"In the book he wrote after the trip, Wanderings of a Spiritualist, he admitted to some disappointment in Australians not being as receptive to the whole idea as he felt they ought to be, and he did face some very hostile crowds."
Some of that opposition was from church groups, and his movement was at times accused — including by illusionist Harry Houdini — of encouraging false hope among the bereaved.
But Doyle's conviction was further consolidated by the appearance of various photographs purporting to show supernatural beings.
The most notorious pictures were taken by two young cousins in a Yorkshire village.
They show the girls "in a garden with fairies" which, Ms Fullerton said, "were later proved to be fakes".
"When [Doyle] came to Australia, he brought with him the photographs that were known as the pictures of the Cottingley fairies, and he claimed that this was absolute proof that fairies existed."
Spiritualist movements remain active today, but with less prominence than during Doyle's public crusade.
He died in 1930, and it could be argued that the fictitious Holmes has enjoyed the more fruitful afterlife, being perpetually re-imagined in film and television productions.
"The curious thing is how many people there are in the world who are perfectly convinced he is a living human being," Doyle can be heard saying in a rare recording from 1929.
"I get letters addressed to him, I get letters asking for his autograph."
To his devotees, Holmes speaks not from beyond the grave, but from between the covers of the books his maker bequeathed to the world.