Double doors

Freud's office: "Will you walk into my parlour?" said the Spider to the Fly. *
* Howitt, Mary, The Spider and the Fly, (1829).

Abandon hope all ye who enter here * 

Dr. Freud's cabinet of horrors was isolated from the outside world. Once you entered, the doors closed behind you, there was no going back. There was the double, sound-proofed door through which the patient entered, and another through which the patient left.
(Freud had an extra door set into his consulting–room wall, so patients could leave discreetly. **)  And between the door was Freud, the sexual healer and drug dealer, with his (in)famous couch, like the spider in the web waiting for the fly to be caught.
Freud was honest about his entrapment. This is how he explained the need for the double doors:
I have had the ordinary door between my waiting room and my office doubled and strengthened by a covering of felt. 

Of course, the felt had a different purpose than strengthening the door. It was intended to dampen any sounds - coming out from Freud's office - of the victims, aka patients, An obvious question to ask is whether the double door opened both ways, or only to let the victim inside.

As Freud further explained:

The purpose of this little arrangement cannot be doubted. Most certainly it can, There's no doubt that - providing sexual services to his patients, with or, sometimes, without their consent - Freud lied about the true purpose.  

As Freud  explained,
it happens ... that people who are admitted from my waiting room omit to close the door behind them; in fact, they almost always leave both doors open.
The cautious people Freud referred to were, of course, his vulnerable female patients, uncomfortable at the prospect of being locked up with an unknown man of bad repute. Freud wasn't tolerating any of it.
As he explained, he who conducts himself in this way  ... belongs to the rabble.
Notably, Freud avoided using the female pronoun, she, even though most of his patients were female. There's no doubt as to the reason why.
Since Freud was providing sexual services to hysterical women of Vienna, as over time he was aiming to become respectable, in this way, Freud tried to distance himself from the sex and sexual treatment of his female patients.

Of course, the female patients' behaviour had nothing to do with them being rabble. They were simply weary of the obnoxious doctor and his suspicious couch.

As Freud saw it:
this negligence of the patient only occurs when he [she] has been alone in the waiting room ... never when others ... have been waiting with him [her].

So, for obvious reasons, the patient didn't want to close the door if there were no witnesses in the waiting room. But when there were other people in the waiting room:

if that latter is the case, he [she] knows ... it is in his [her] interest not to be listened to while he [she] is talking to the physician, and never omits to close both the doors with care. ***

Freud's claims are an obvious subterfuge. The soundproof doors were needed to dampen the cries of the women on the Freudian couch. Even if someone was in the waiting room, no one could hear their cries.

Freud couldn't keep a secret, blabbing about how he was subjugating his female patients.
* Alighieri, Dante, Inferno, 14th century. (Ciardi, John translation, 1954).

** Burke, Janine, The Gods of Freud,  (2006, p. 240).

*** Freud, Sigmund, A general introduction to psychoanalysis, (1920. p. 212).