Besoin et Fonction

A saying I remember from conversations with my uncle forty-odd years ago, and I’ve never found it in print, so take the wording as mine-via-his.

Le besoin fait la fonction. L’absence de besoin défait la fonction

In any system, where there is a need, a function that meets it tends to emerge; remove the need and the function decays. The nearest English idiom, “necessity is the mother of invention,” misses twice: it implies an inventor (this is agent-less — the system produces the function, no one has to design it), and it only runs one way (English has no maxim for the un-making). Vestigial organs are the obvious case.

There’s a faint echo of the old “la fonction crée l’organe”, but I won’t pretend that’s where it comes from.