Literal Translation
Make long fire/not make long fire
Actual Meaning
To drag on and end in failure/not to last
Etymology
I got confused with this one, I hadn’t realised that the two expressions aren’t actually related or opposites! ‘Faire long feu’ refers to an event or circumstance that drags on and on, only to ultimately fail. This expression dates back to the early days of firearms, when cannons and rifles had to be loaded before each shot. If the powder was damp, went out or took too long to burn, the gunners would miss their target. We therefore use ‘faire long feu’ when talking about a long action that leads to failure.
‘Ne pas faire long feu’, on the other hand, has its origins in a real blaze. It is based on the image of a straw fire: fast, fleeting and relentless. It is used to describe a situation that does not last.
Another explanation refers to Greek mythology and one of its heroes: Meleager. The existence of this great hunter was closely linked to the burning ember of a hearth. The myth has it that when the ember burned out completely, Meleager’s life would be taken, showing in a rather unsubtle way that his life was ephemeral (ephemerous?).