ax to grind vs indifference

ax to grind

noun
  • A grudge or grievance, with implications of confrontation. 

  • A proposition or point of view to advocate, especially motivated by self-interest. 

indifference

noun
  • Unconcerned nonchalance. 

  • The state of being indifferent. 

  • Unbiased impartiality. 

  • Unemotional apathy. 

  • Self-identity defined through the negation of difference, non-difference. 

  • A lack of enthusiasm. 

How often have the words ax to grind and indifference occurred in a corpus of books? (source: Google Ngram Viewer )