gild the lily vs improve

gild the lily

verb
  • To embellish or improve something unnecessarily. 

  • To add superfluous attributes to something. 

improve

verb
  • To make (something) better; to increase the value or productivity (of something). 

  • To become better. 

How often have the words gild the lily and improve occurred in a corpus of books? (source: Google Ngram Viewer )