fire in the belly vs inclination

fire in the belly

noun
  • The emotional stamina and vigor, passion, or inner drive to achieve something, to take action, etc. 

inclination

noun
  • A tendency. 

  • The angle of intersection of a reference plane 

  • A physical tilt or bend. 

  • A slant or slope. 

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