flexible vs hold the line

flexible

noun
  • Something that is flexible. 

adj
  • Capable or being adapted or molded in some way. 

  • Capable of being flexed or bent without breaking; able to be turned or twisted without breaking. 

  • Willing or prone to give way to the influence of others; not invincibly rigid or obstinate. 

hold the line

verb
  • To firmly maintain one's viewpoint, principles, or situation; to refuse to change one's practices or plans. 

How often have the words flexible and hold the line occurred in a corpus of books? (source: Google Ngram Viewer )