pangs of conscience vs rue

pangs of conscience

rue

verb
  • To repent of or regret (some past action or event); to wish that a past action or event had not taken place. 

noun
  • Any of various perennial shrubs of the genus Ruta, especially the herb Ruta graveolens (common rue), formerly used in medicines. 

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