discourage vs sustain

discourage

verb
  • To persuade somebody not to do (something). 

  • To extinguish the courage of; to dishearten; to depress the spirits of; to deprive of confidence; to deject. 

noun
  • Lack of courage 

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. 

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