Voltaire was quoting an Italian proverb when he included this in his Dictionnaire Philosophique (1770). He later opened his moral poem La Béguele with the lines "In his writings, a wise Italian / Says that the best is the enemy of the good".
The saying has been described as a manifestation of the so–called 'golden mean' – the idea that in between any two extremes there is an ideal middle path. As an example, Wikipedia explains that in Aristotelian philosophy, courage is a virtue; but in excess it would manifest as recklessness, and in deficiency as cowardice.
Confucius is supposed to have said "Better a diamond with a flaw than a pebble without." And in Shakespeare's King Lear, the Duke of Albany remarks that "Striving to better, oft we mar what's well.' (Spark Notes helpfully translates this for the modern teenager: "people often screw things up trying to make them better.")
© Haydn Thompson 2020