BOSTON - To get to the famous Ether Dome at Massachusetts General Hospital, you must first negotiate the hospital itself - an intense experience at any hospital, but especially at this renowned medical hub.

At MGH on a gleaming Monday in late September, ambulances pull up to the emergency unit. In the busy main foyer and its connecting corridors, you dodge wheelchairs and nurses and brisk doctors in blue scrubs.

A man with severe burns to his head is sipping coffee as he converses quietly with a woman, possibly his wife. A young girl with dark eyes and fresh olive skin wanders into the gift shop. She wears a gown, and her right hand clutches an IV pole.

A Franciscan friar with a long white beard emerges from the hospital chapel. He is one of a host of "spiritual care residents" sharing office space on the premises.

What stories these people must hear on a daily basis! What mortal predicaments.

One of the world's leading hospitals, MGH is also the teaching hospital for Harvard Medical School. It dedicates itself to putting massive intellectual firepower in the service of bewildered, suffering humanity. It has its own institutional history, some of which you can see as you wander the corridors.

At the end of one busy thoroughfare, for instance, there's a copy of the original MGH Charter, enacted Feb. 23, 1811. The charter obliged the hospital to undertake the care of "such lunatick and sick persons as may hereafter be chargeable to the Commonwealth."

Nearby, a display of posters highlights the achievements of women in medicine at MGH. There are also two lovingly rendered scale models, each made from painted plaster and about the size of a dining room table, showing the site as it was in 1776 and 200 years later.

Better than any of this, though, is the Paul S. Russell, MD Museum of Medical History and Innovation. Housed in a modern glass building, it's just a short walk from the hospital's main foyer. Displays cover everything from early medical instruments (forceps, tongue depressors and tonsillotomes, also called tonsil guillotines) to MRI coils.

There is a surgeon's kit from 1865 - the end of the Civil War - that includes ivory-handled instruments for amputating, trepanning (drilling holes into the skull) and ophthalmology. And there is a child's MRI helmet from 2011 that comes with an algorithm to correct for movement as it scans kids' brains.

It's all very impressive. Yet somehow, none of it is quite as compelling as the parade of humanity in the hospital corridors, which you pass on your way to the Ether Dome. It's on the fourth floor of the hospital's original Bulfinch Building - a large granite Greek Revival structure dwarfed by and connected to the modern buildings around it.

The Ether Dome is famous for good reason. In this room on Oct. 16, 1846 (otherwise known as Ether Day), William T.G. Morton successfully trialed the first use of sulfuric ether as an anesthetic on a surgical patient. The impact was world-changing. Before anesthesia, some people chose death over surgery because it was such an excruciating ordeal.

The Ether Dome served as MGH's operating theater from 1821 to 1867. The site's significance comes into focus when you learn why the room was positioned where it is - separate, and elevated. There were two main reasons: to maximize natural light and to muffle the screams of surgical patients, thereby saving the equanimity of everyone else at the hospital.

Morton's colleague, MGH surgeon and Harvard Medical School professor Henry Jacob Bigelow, wrote an article describing the experiment. The news traveled quickly around the world.

To arrive at the Ether Dome after wandering the hospital's corridors is to have the momentousness of the discovery brought home. Hospitals try to look functional and bureaucratically impersonal; but what goes on there on a human level is intensely, exhaustingly emotional. More than that, it's existential. People's lives are on the line. They're fighting battles. Many are losing.

So it's a strange, unanticipated kind of privilege to find yourself in their company. Where would so many of these people be - how would their battles be going - without anesthesia?

The Ether Dome has amphitheater-style seating and is still used for lectures (so it's a good idea to phone ahead to check that it won't be booked). Prominent on the wall is a 2000-01 oil painting of the famous experiment by Lucia and Warren Prosperi. It pales, perhaps inevitably, in comparison to paintings of similar subjects by Rembrandt and Thomas Eakins. But its scale and explicitness - bow ties, beards and copious blood - make it weirdly engrossing.

Also on display are a plaster cast of the Apollo Belvedere, a teaching skeleton and an Egyptian mummy, fondly referred to as "the hospital's oldest patient." As America's first complete Egyptian burial ensemble, the mummy spent much of the late 19th century at Boston's Museum of Fine Arts. It's not immediately clear why it's displayed in the Ether Dome, but there are solid links.

In 1823, John Collins Warren, MGH's co-founder and head surgeon, partially unwrapped the mummy and performed a (very belated) post-mortem. The Egyptian man's head, blackened from decay but still sporting white teeth, remains uncovered from that time. Warren, who was an important witness to the dramatic events in the dome on Ether Day, also published the first American treatise about mummies and mummification.

In 1960, Dows Dunham, a curator at the MFA Boston, translated the hieroglyphics on the coffin and discovered the corpse's name: Padihershef. X-rays were taken at various points, and in 2013, Padihershef was given a full-body CT scan by MGH radiologist Rajiv Gupta.

But there's another reason that Padihershef belongs in the Ether Dome. Mummies are ancient artifacts that speak to the mysteries that congregate at the trembling border between life and death.

Anesthesia, too, is a mystery. It is used at places like MGH every day. But as Kate Cole-Adams conveys in her 2017 book, "Anesthesia: The Gift of Oblivion, the Mystery of Consciousness," the astonishing thing about anesthesia is that we still don't understand how it works. What that in turn implies is that we still aren't able to define consciousness.

Walk back through the busy corridors of MGH, its atmosphere charged by the operations of advanced science, sober decision-making and swirling emotions. ... So many individual brains, each one attached to a mortal body and harboring its own flickering thoughts. What is going on here? The idea that we don't really know seems incredible.

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Ether Dome at Massachusetts General Hospital, 55 Fruit St., Bulfinch Building, Fourth Floor, Boston. massgeneral.org/museum/exhibits/etherdome.