Why do we say "If it ain't broke, don't fix it"?

Meaning:

Don't try to improve on a system that already works

Background:

This folksy variation of older expressions such as "leave well alone" or "let sleeping dogs lie" appears to have originated in the USA during the 20th century. The first recorded usage was by Government official Bert Lance writing in a May 1977 issue of Nation's Business.

More expressions and their source

Challenge yourself with BookBrowse Wordplays