hark back vs progress

hark back

verb
  • To return to where one has previously been; to retrace one's steps. 

  • To allude, return, or revert (to a subject previously mentioned, etc.); also, to evoke, or long or pine for (a past era or event). 

  • To call back (hounds); to recall. 

  • Of hounds: to retrace a course in order to pick up the lost scent of prey. 

noun
  • An act of hounds retracing a course in order to pick up the lost scent of prey. 

  • An act of alluding, returning, or reverting (to a subject previously mentioned, etc.); also, an act of evoking, or longing or pining for (a past era or event). 

progress

verb
  • To move, go, or proceed forward; to advance. 

  • To develop. 

  • To expedite. 

  • To improve; to become better or more complete. 

noun
  • Specifically, advancement to a higher or more developed state; development, growth. 

  • Movement onwards or forwards or towards a specific objective or direction; advance. 

  • An official journey made by a monarch or other high personage; a state journey, a circuit. 

  • Movement or advancement through a series of events, or points in time; development through time. 

  • Science has made extraordinary progress in the last fifty years. 

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