Their Family Business? The Other Dimension.

Lisette Coly and Anastasia Damalas are at a crossroads.

But, on a recent late-winter morning, they were also in the book-filled storefront of their foundation in the Greenport section of Long Island, when someone knocked at the door.

Ms. Coly, 71, and her daughter, Ms. Damalas, 32, were leery. Their family nonprofit is appointment-only, and no appointments were scheduled.

In walked a woman who said she had driven from Eatons Neck because she was interested in buying the building. She requested a tour, but Ms. Coly told her the foundation was closed for the day.

Still, the woman made her way into the quiet and pristine space, toward the back archive where Ms. Coly had just unveiled 90-year-old photos of her grandmother that had never been shown to the public. The photos feature Eileen J. Garrett, the celebrity medium of the 20th century, deep in trance.

The uninvited visitor surveyed the room and left in a huff.

“That was highly irregular,” Ms. Coly said afterward. But it was not the only bizarre occurrence that day: lights flicked on when their switches were in the off position, and loud, electrical buzz sounds intermittently came on and off.

Could such events be paranormal — related to the appearance of the rare photos? Some might think so. Others might correlate them to the ordinary problems of this mundane world: an aging, 87-year-old building and a cutthroat real estate market.

Because after 17 years in this location, and a little over 70 years in business, the mother-daughter proprietors of the Parapsychology Foundation are about to lose their lease.

At risk is the enormous, one-of-a-kind Eileen J. Garrett Library, a staggering archive of books, scholarly papers, photographs, letters and some 600 videos documenting the broad and complicated field of parapsychology in the 20th century.

“My grandmother used to say, ‘Monday, Wednesday and Friday I believe in the paranormal. Tuesday, Thursday and Saturday I don’t. And Sunday I don’t give a damn,” Ms. Coly said, relating to the weariness that comes with steering a precarious nonprofit. “After all these years, I feel the same way.”

Ms. Coly and Ms. Damalas’s financial predicament — their landlord is selling the building in Greenport and they cannot afford to buy it — highlights a fork both in their livelihood and the cultural trajectory of the discipline itself.

Parapsychology, a term coined in 1889 by the German psychologist and philosopher Max Dessoir for the scientific investigation of psychic or paranormal phenomena, often refers to the experimental approach to the field. It pursued many of the questions now studied by hard sciences like physics and neuroscience, yet today is wildly misunderstood by the general public. New science and research are either lost in academic echo chambers or reduced to haunted house explorations on TV.

But Ms. Coly and Ms. Damalas believe the foundation and its library can still help people if the study of the paranormal can be reframed in a contemporary light.

“I’ve been a good soldier. I’ve played within the rules of academia. But everything is morphing. We need to move with the times,” Ms. Coly said. She wants to save, grow and digitize the library and find a good home for it. “I refuse to see it broken up.”

A Trance Medium to Salvador Dalí and Anais Nin — and an Inspiration for Auntie Mame

Eileen J. Garrett did not have an easy start. She was born in Meath, Ireland, in 1893 and was orphaned over the next couple of months when both parents died by suicide. She was then adopted and raised in Meath by her aunt and uncle.

As a young girl, Ms. Garrett said she started seeing apparitions, hearing voices and predicting future events. When she moved to London at age 15, she found a mentor, the spiritualist James Hewat McKenzie, and attended the school he founded — the British College of Psychic Studies in London — in the 1920s.

She and Mr. McKenzie determined that she was a trance medium — as opposed to a more run-of-the-mill psychic — when she began channeling an entity named Uvani, whom she called her “control.” From that point forward, Uvani performed the role of communications director between the entranced Ms. Garrett and the various entities who wanted to speak through her.

Ms. Garrett and Uvani fit in with the religious trend of the day: Spiritualism. But Ms. Garrett did not subscribe to the Spiritualist doctrine, openly admitting her own disbelief in survival of consciousness.

A skeptic herself, she worried that her psychic sensitivities, as they’re called, were early signs of madness. But after multiple visits to psychiatrists who gave odd diagnoses — that her behavior was a stress response to her husband’s sexual inadequacy, for example (she was married three times total) — she committed to managing her experiences and finding answers on her own.

“My grandmother refused to think everything mysterious was a ghost,” Ms. Coly said. “She thought just as likely that she had multiple personalities, or was using telepathy, or some other phenomenon that wasn’t yet understood.”

“Voice hearing exists on a continuum,” said Philip Corlett, a clinical researcher who is leading an N.I.M.H.-funded study of clinical and nonclinical voice hearers with James Gold at the Maryland Psychiatric Research Center and Connecticut Mental Health Center in New Haven. “So clairaudience” — or receiving auditory messages in one’s head — “is not necessarily a sign of mental illness.”

In a previous study in Connecticut, Dr. Corlett and his colleagues found, after testing patients and nonclinical voice hearers, that psychics did not meet diagnostic criteria for a psychotic illness. “The psychics in the study were in fact hearing voices, but we’ll have to agree to disagree on the provenance of those experiences” — meaning the data doesn’t show they have mental illness, but he also doesn’t believe they are talking to the dead.

Ms. Garrett’s own skepticism about her psychic abilities captivated Harry Price, a Spiritualist debunker and psychical researcher known today as “the first ghost hunter.” In 1930, Mr. Price arranged a séance of Ms. Garrett’s in which she was asked to contact Arthur Conan Doyle, the recently deceased creator of “Sherlock Holmes.”

Instead, Uvani brought through the deceased pilot of a crashed blimp, the R-101, that had fallen in France two days earlier. The seemingly sensitive information she channeled — that the engines were too heavy; it was flying at too low of an altitude; an oil pipe was plugged — caught the attention of reporters in attendance.

Though dismayed by her sudden fame, Ms. Garrett moved to the United States the next year and went on a lecture tour for the American Society for Psychical Research.

In New York, Ms. Garrett worked as “a 9 to 5 psychic,” as she herself put it, establishing offices at 29 West 57th Street, and attracting high-profile clients, including Aldous Huxley, Salvador Dalí, Henry Miller and Anais Nin.

As a teenager, Ms. Coly started helping out around her grandmother’s office, getting dispatched to do things like tell Mr. Dalí that Ms. Garrett was busy when he came though the door: “‘He’s such a bore,’” Ms. Coly recalled her grandmother saying.

Ms. Garrett was not your conventional granny: At one point she implored her young granddaughter to take LSD with her and Mr. Huxley. Ms. Coly refused. “She didn’t exactly say I was a wuss,” Ms. Coly said, “but she tried to persuade me, saying, ‘What’s the worst that can happen? We can’t guarantee you an easy time, but we can certainly get you out of it — eventually.’”

But Ms. Garrett attracted plenty of willing acolytes. Her young administrative assistant, Ed Tanner, wrote the novel “Auntie Mame” under the pseudonym Patrick Dennis, and told Ms. Garrett he had based his title character partly on her.

Two Friends and a Mission

The Parapsychology Foundation, which today is the largest collection of parapsychological research in the United States and third largest in the world, was started in 1951 by Ms. Garrett and her close friend Frances P. Bolton, a Republican congresswoman from Ohio.

Their mission was to widely fund the study of consciousness, particularly the aspects known as paranormal or “psi.” The two women supported decades of scientific and academic research with Ms. Bolton’s inherited oil money (her uncle was a partner of John D. Rockefeller).

They funded research internationally, including Joseph Banks Rhine’s early ESP studies and Ian Stevenson’s examination of reincarnation; the exploration of religious miracles at Lourdes, France; and the United States government’s early interest in “remote viewing,” the now famous declassified psychic spy program.

The foundation has been strictly matrilineal: Ms. Coly’s mother, Eileen Coly — the only survivor of Ms. Garrett’s three children; two sons had died young — assumed the role of president of the foundation upon Ms. Garrett’s death in 1970. Lisette Coly took over the presidency in 2012.

Over the course of Ms. Coly’s tenure, she has maintained the library, continued providing grants, brought back the Helix Press imprint and served as the editor in chief of the International Journal of Parapsychology. She has also published proceedings of all of the foundation’s 41 international conferences, many of which she helped coordinate over the years, featuring experts in neurobiology, dream research, ceremonial magic and areas of pharmacology that included psychedelics.

“My grandmother always wanted to bring together various disciplines to look at the phenomena,” Ms. Coly said. “She didn’t want parapsychology talking to itself as a field.”

These days, without Ms. Bolton’s generous check writing, which ended with her death in 1977, the foundation leads a quieter existence for a few dozen visitors a month: students, researchers and laypeople who seek answers to what they think may be paranormal questions. Since 1977, the foundation has subsisted from a modest endowment left by Ms. Bolton and the occasional bequest, but those are few and far between.

An Unwieldy Inheritance

The library, perhaps the foundation’s most valuable physical asset, is a gold mine. “It’s really an information clearinghouse” of vetted, peer-reviewed, quality information and rare primary source materials, Ms. Coly said. “You won’t find any books on werewolves.”

The foundation has moved two times before: First, in 1988, from the 57th street address to a brownstone on East 71st street between Second and Third Avenues — Ms. Coly’s home — a move that lasted until 2004, when the collection went into storage. In 2005, the storefront rental in sleepy Greenport came along.

“People who are searching in this realm, no matter what level, should have a physical place to go,” Ms. Coly said. “You don’t have to be a card-carrying believer to be curious. The phenomena should be discussed in normal parlance, and information should be available.”

Ms. Coly and Ms. Damalas are re-evaluating how to best guide the foundation into the future. The old model was only sustainable with a rainmaker like Ms. Bolton. Conferences and research require money and don’t bring in enough revenue alone.

For reasons of quality and reputation, Ms. Coly and Ms. Damalas are reluctant to use the flashier, income-driving models from the spiritual marketplace, like recreational ghost hunting or expensive sessions with mediums.

“I don’t want to play games with the phenomena on the foundation’s time,” Ms. Coly said. “This is not about seeing if there are ghosts in an old building.”

Ms. Damalas is busy digitizing materials, building a social media presence, creating YouTube videos and listening in on daily calls about the library’s future location. The foundation has always aimed to serve two audiences: academia and the general public.

Ms. Coly remembered some of the calls she has handled.

“Parents call wanting to help their children who they worry might be possessed. Or after 9/11, someone called wanting to know if souls could be trapped on a plane. People need help getting through the experience, whether or not it is paranormal. And that does not mean sending them to a random psychic on the street.”

Ms. Damalas, perhaps because of her proximity to the family vocation, has had difficulty handling paranormal questions in her own life. While a new area of research is exploring psychic sensitivity as a genetic inheritance, Ms. Damalas hesitates to embrace trance mediumship, even though she’s had “incidents” her whole life.

When I asked for an example, an amused Ms. Damalas shared a series of stories, one about her childhood realization that a restaurant her family frequented on Long Island didn’t actually have a haunted theme.

Upon understanding that no one else saw the macabre atmosphere, Ms. Damalas became perpetually guarded. Like her great-grandmother, she “sleeps with the lights on.”

In general, she said, “I think our materials can really help people find comfort. I could imagine a building in the city, with membership, and a Soho House-like atmosphere. I think that would be really cool. But do I want spirits in my face? No. I do not.”