What a lila actually is, and what it is not.

A lila is an all-night ceremony. It begins after dark, usually with a procession and a meal, and it ends at the dawn call to prayer. Between those two points a maâlem and his musicians work through a sequence of rhythms, each associated with a colour and with a particular spirit, and people in the room dance — not socially, and not for anyone watching.

The word most often used in English is trance, which is accurate enough and carries the wrong associations. What happens is closer to a controlled, communal, extremely long piece of work with a therapeutic purpose. Somebody is unwell, or troubled, or has asked for the ceremony for a reason the room mostly knows. The music is the method.

The structure is not improvised. The colours come in order. Each section has its rhythms, its songs and its incense, and the maâlem moves through them with an attention to pacing that is obvious once you know to look for it — he is watching the room and deciding how long a section needs, which is a different skill from playing.

What visitors find hardest, in my experience, is that nothing is being performed at them. There is no stage, no front, and no applause at any point during the night. You are in a room where something is being done. The correct posture is to sit, drink the tea you are given, and let several hours pass without reaching for your phone.

It is also long, and the length is the point rather than an inconvenience. Around two in the morning most first-time visitors hit a wall. Around three, if they stay, something changes. Almost everybody who makes it to the dawn call says a version of the same thing afterwards, which is that they cannot explain what happened in the last two hours and would like to come back.

One practical note. Photography during a lila is usually unwelcome and occasionally offensive, and the moments most worth photographing are exactly the ones where it is most unwelcome. Ask, accept the answer, and take the night home in your head instead.