sustain vs vary

sustain

verb
  • To encourage or sanction (something). 

  • To provide for or nourish. 

  • To maintain, or keep in existence. 

  • To allow, accept, or admit (e.g. an objection or motion) as valid. 

  • To keep from falling; to bear; to uphold; to support. 

  • To confirm, prove, or corroborate; to uphold. 

  • To aid, comfort, or relieve; to vindicate. 

  • To experience or suffer (an injury, etc.). 

noun
  • A mechanism which can be used to hold a note, as the right pedal on a piano. 

vary

verb
  • To be or act different from the usual. 

  • To make of different kinds; to make different from one another; to diversity; to variegate. 

  • To embellish; to change fancifully; to present under new aspects, as of form, key, measure, etc. See variation. 

  • Not to remain constant: to change with time or a similar parameter. 

  • To institute a change in, from a current state; to modify. 

  • To change with time or a similar parameter. 

  • To display differences. 

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