fade away vs run its course

fade away

verb
  • To lose strength, become weaker; to wane; to disappear or reduce slowly. 

noun
  • A technique of painting young women, by having their clothes fade into the background. 

run its course

verb
  • To come to a natural end. 

How often have the words fade away and run its course occurred in a corpus of books? (source: Google Ngram Viewer )