instability vs sagacity

instability

noun
  • The quality of being unstable. 

  • A state that is not in equilibrium, or in which a small change has a large irreversible effect. 

sagacity

noun
  • See Thesaurus:wisdom 

  • The quality of being sage, wise, or able to make good decisions; the quality of being perceptive, astute or insightful. 

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