<P> The original meaning may have been that attempts to improve something may actually make it worse, similar to the sentiment expressed in the maxim "leave well enough alone". Neither the Shakespeare nor the Voltaire construction suggests perfection, only improvement, lending support to this interpretation . </P> <P> Earlier, Aristotle, Confucius and other classical philosophers propounded the related principle of the golden mean, which counsels against extremism in general . </P> <P> The Pareto principle or 80--20 rule is a 20th - century analogue . For example, it commonly takes 20% of the full - time to complete 80% of a task, while to complete the last 20% of a task takes 80% of the effort . Achieving absolute perfection may be impossible and so, as increasing effort results in diminishing returns, further activity becomes increasingly inefficient . </P> <P> The idiom "The devil is in the details" </P>

Who said perfect is the enemy of done