In 1991, the New York City subway was plastered with enormous couch posters, part of an ad campaign by the Archdiocese of New York. They bore the caption (some in English, others in Spanish), “Some people find the same peace of mind sitting in a pew. Come home at Easter. The Catholic Archdiocese of New York.”

As a young psychiatrist and candidate in psychoanalytic training in Manhattan, I was taking the subway four times a week to my analyst’s office to lie on just such a couch. These ads were obviously not aimed at psychoanalytic trainees like me. But who, I wondered, comprised the target audience? And why was the Church so confident that subway riders would easily decode the image, and understand the implied link between couch and pew?

The couch endures as a symbol of self-reflection and healing. It’s shorthand for the therapist in cartoons and movies, even as the popularity of psychoanalytic treatment wanes. We could say the couch is healthier than the field of psychoanalysis itself, and I would add that its iconic status in culture contrasts with how it’s increasingly viewed by contemporary analysts, many of whom see it as a relic of a more authoritarian era, a power play on the part of the analyst that supposedly blocks the path to authentic emotional engagement. Are they right? The research hasn’t been done, so we can’t know which patients will find it liberating, and which discomfiting.

Freud said he asked patients to lie on a couch because he couldn’t stand being stared at all day

Freud famously said that he got patients to lie on a couch because he couldn’t stand being stared at all day, but he never explained why a recumbent posture should be preferred to simply arranging the chairs so that analyst and patient didn’t face each other. Freud’s couch, heavily decorated with rugs, pillows and blankets, and surrounded by his extensive collection of antiquities, has the look of a Turkish divan. It speaks volumes about its owner’s taste and interests. Most contemporary analysts prefer the more spartan couch seen in cartoons and illustrations today. Even analysts who have forsaken the couch often retain one as part of their office décor.

For such an enduring icon, it’s surprising the origins of its use have never been fully explored; the analytic literature is strangely silent on the subject. Following Freud, the couch became a fixture of analysts’ offices, but no one seemed to know why.

If analysts can’t offer any insights, maybe social history could. When I began to research Greek and Roman customs of reclined dining, I found that far from symbolising submission to medical authority, recumbence in social settings has long served as an expression of freedom, pleasure, luxury and intimacy. But by the 19th century and beyond, it became less socially acceptable.

Even today it’s difficult to know with any degree of certainty who is best suited to using the couch during treatment – although I continue to recommend it to most patients I treat. But I don’t insist on it, and try to gauge the patient’s interest first.

Ideally, both analyst and patient are able to access deeper layers of thought and feeling once freed from the usual social cues of face-to-face interaction, but only testing it out will tell. Good analytic technique calls for flexibility and sensitivity, not for the doctrinaire insistence on one posture or another. Although it’s fair to say that reclining for the purpose of talking to someone is for many people a uniquely powerful experience that has no parallel anywhere else. •

To order a copy of On The Couch: a Repressed History of the Analytic Couch from Plato to Freud by Nathan Kravis (MIT Press; £24.95) for £21.21, go to bookshop.theguardian.com