Cinema is a mass medium. And since we film-makers want to get as many people as possible to see our films, we try to find a common denominator. But we also want each person in the audience to feel the film is whispering things only they know about. We want to achieve a paradoxical mass-intimacy.

There are four key ways in which film attempts this – and manages it better than any other art form. Three of them occur irrespective of whether we are watching a film on an iPad or in an Imax. But the fourth – and possibly most crucial – is singular to seeing a film in a cinema.

It’s important to appreciate them all in order to know what we have lost while cinemas are shut. And also what the medium must rely on if its future lies off the big screen.

1. A life held in perfect balance

When a film connects, it speaks to the head, the heart and the gut. Each of these ways of thinking – intellectual, emotional and instinctual – is directly addressed, then woven together and rendered mutually coherent. We are served something we all long for but rarely experience: our lives seeming to be in miraculous balance.

Cinema is especially powerful because it can communicate directly with those pre-linguistic intelligences that lie within us. The question and the responsibility for film-makers is how to harness that power for the good, because it can easily be misused. For at its best, film could supply the braided coherence ordinary life does not.

Such films would fulfil a unique social, almost spiritual, function, helping people to resolve contradictions within themselves, and then to align with each other in a healthy society.

2. Deep secrets finally shared

Audiences are often surprised by a film’s apparent intimacy with their own inner secrets. This is the result of a film-maker judiciously deciding what to put in and what to leave out. If a film shows too much, the audience just has to sit there and take it, but they won’t feel a personal, emotional bond with the story or the characters. But if certain things are left incomplete, to just the right degree, everyone will use their own particular imagination to turn the partial into the complete.

That is why people often differ in their sense of what a film has shown them. They may think they have seen the whole, but they are unaware some of the crucial elements have come from within. So in a sense they are seeing themselves in the story. As John Huston said: “The real projectors are the eyes and ears of the audience.”

3. Authorised voyeurism

As we watch a film, we are allowed to gaze deeply into the eyes of beautiful, ugly, powerful, scary, interesting people. We invade their space. In daily life, such close access is not often available. The people on screen, however, seem not to know that we are watching them, which makes it even more intoxicating. All it would take would be for them to shift their eyes a few degrees, look into the lens, and we would be found out. But until then, we can watch with fascination as thoughts and emotions pass like shadows, storms, and beams of sunlight across their faces.

This proximity to beauty and power, mediated through eye contact, goes far back into our primate past. Cinema is the one art form that has found a way, through creative use of the close-up, to tap deeply into the wellsprings of this primitive and almost irresistible force of nature.

4. The discomfort of strangers

For the past two months, we have watched films only at home. But a film’s agency also depends on it being seen in a cinema at an appointed time, in the dark, in the presence of strangers also drawn to this moment.

Under the right circumstances, a theatrical screening deeply enhances the experience of cinema. A lot of what can be said about this veers into the mysticism of collective consciousness – hard to quantify but certainly intangibly present. If we could somehow render visible the emotions and thoughts of an audience in the sway of a good film, it would probably resemble the beautiful arching loops we see with large flocks of birds or schools of fish.

There is also the fact that when we leave our houses, at some expense (babysitters, popcorn), a little discomfort (parking, public transport), and risk (strangers! Infection!) and we gather in a cinema at a specific time, we are – by those very actions of expense, displacement, constraint, and risk – primed to see the film in a more expanded way than when we summon it on a streaming service.

Technically, the quality of a film at home can now equal, or exceed, the quality at a multiplex. But what at-home viewing can never do is provide a communal experience to which we happily submit. In the best circumstances, that experience can paradoxically expand our consciousness and awareness of our commonality, sharpening our senses in the mass intimacy of the darkened theatre.

And when we are in the dark, with many other people, we are especially alert to tiny signals from the audience that will trigger group laughter, screams, or tears. At home, alone, or with a few others, these signals are reduced proportionally. The larger the audience, the more likely it is that someone will get the joke early, and that first laugh will trigger everyone else. At the end of a live performance, there is a moment when the audience is ready to applaud, but uncertain of exactly the right moment. But as soon as someone claps, everyone will follow along.

Humans have been assembling in the dark, listening to stories, since the invention of language. It is indelibly part of who we are and how we bond with each other. The theatrical experience is a recreation of this primeval gathering, the flames of the campfire replaced by shifting images that are telling the story itself.

After the current hurricane has blown through the world, and we begin to pick up the scattered pieces, will cinema exhibition return to the way it was? Probably not in every detail – the universal lockdown has been an unprecedented shock. But I believe the deep human need to leave the isolation of home and gather in the fire-lit dark with like-minded others will provide an irresistible channel to guide the reopening of cinemas – and even, perhaps, their reinvention.

Walter Murch’s films include The Godfather trilogy, The Conversation, Apocalypse Now, American Graffiti and The English Patient.