What's gilding the lily?
To gild something is to cover it with a thin layer of gold or something else smooth and shiny.
The lily is the flower. To gild the lily is ridiculous - not to say downright impossible - but that's the point. The lily is beautiful as it is. To further adorn it will be, quoting Shakespeare, "much ado about nothing".
In fact, gilding the lily the expression comes (indirectly) from Shakespeare, who wrote in the 16th century: "To gild refined gold, to paint the lily, to throw a perfume on the violet, to smooth the ice, or add another hue unto the rainbow… is wasteful and ridiculous excess" (The Life and Death of King John).
Shakespeare of course said "paint the lily", which made sense. Today, people say "gild the lily", and they do it too.
In China, we have a similar expression. It's called "adding feet to a snake". In a parable first told some 2,000 years ago, two people were awarded a bottle of wine and they so arranged that the first one to finish the drawing of a snake would have the drink. One of them had quick hands with the brush and he finished the paint first. Instead of drinking the wine outright, however, he said to the other smugly: "I think I can even add a few feet to it before you're done with yours." But while he was at it, the other man wrapped up his snake, feetless of course, and drank the wine before asking: "Have you ever seen a snake with feet?" The first man was left to rue his ingenuity.
The moral of the story? If you have extra energy, you'd do better by getting yourself, like, a drink. Without the gild the lily is beautiful. Without feet the snake is complete. Do not mess with them.
This point of less is more is driven home humorously by the late philosopher Alan Watts (Google him), who in one of his lectures likened "gilding the lily" to "putting a beard on a eunuch."
You get the picture.