French guy here: never heard of "une toile exige un mur".

Not a single result in French also.

I know there's a (more popular?) saying that is very similar but can't remember it atm.

Are you sure? I thought it was Renoir or Batut, or Bresson, or perhaps Watteau, who, when asked for his most useful advice to a new artist, famously uttered this short and mysterious phrase. Could have sworn LaBeouf quoted it in an interview after he collaborated with artist Cantor on their magnum opus.

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wiether 2 hours ago | parent [-]

It could be a niche quote in an art history book, but it could hardly be qualified as a saying.

I asked around since my first comment and not a single person knew about it.

	▲	publicdebates 2 hours ago \| parent [-]
		It's so memorable, probably why it stick in my memory: how can you have a canvas without a wall? The wall is the canvas. Yet the wall simultaneously constrains the canvas, thus allowing it to become the canvas, to become worthy of a canvas. This French idiom says so much without saying practically anything.