encourage vs foment

encourage

verb
  • To mentally support; to motivate, give courage, hope or spirit. 

  • To spur on, strongly recommend. 

  • To foster, give help or patronage 

foment

verb
  • To incite or cause troublesome acts; to encourage; to instigate. 

  • To apply a poultice to; to bathe with a cloth or sponge. 

noun
  • Fomentation. 

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