When and why do we say ne pas avoir la lumière à tous les étages?

Lyon’s annual Festival of Lights (Fête des Lumières) began this weekend (December 5) with around 30 installations and light shows dotted around the city, to be enjoyed until Monday (December 8).

On the subject of lumière, we thought of the expression: ne pas avoir la lumière à tous les étages.

We look at what is means and how to use this popular phrase in everyday French. 

What is the meaning of ne pas avoir la lumière à tous les étages?

It literally translates as: to not have light on every floor. 

It is used to refer to someone who is not very intelligent and could also be described as dimwitted or not very ‘switched on’.

It conjures up an image of the different levels within someone’s brain failing to light up, as a piece of information or idea fails to permeate their understanding.

An equivalent expression in English might be ‘the lights are on but nobody's home’, or ‘they are not the sharpest tool in the box’.

What are the origins of ne pas avoir la lumière à tous les étages?

It has been suggested that it may relate to the phrase ‘ne pas être une lumière’, an expression used since the 17th Century to describe someone who is not intelligent.

Here, ‘lumière’ is employed with reference to intelligence in a similar way to the word ‘bright’ in English.

This expression is also linked to the Lumières period (the Age of Enlightenment), which was an era of cultural, philosophical, literary and intellectual progress beginning in the second half of the 17th Century in Europe. 

It involved French thinkers such as Voltaire and Denis Diderot, and the way it redefined knowledge, culture and ethics influenced the reasoning behind the French Revolution among other events.

To whom do you say ne pas avoir la lumière à tous les étages?

It is a commonly-used informal phrase that can be said around friends and family. 

Some people may find this expression slightly offensive, especially in a formal or professional environment. 

Alternatives to ‘ne pas avoir la lumière à tous les étages’ include:

• Ne pas avoir inventé l’eau chaude - literally: to have not invented hot water
• Ne pas avoir inventé le fil à couper le beurre’ - literally: to have not invented the wire to cut the butter
• Avoir été bercé trop près du mur - literally: to have been rocked too close to the wall