let go vs rein

let go

verb
  • To ignore (a comment, etc.). 

  • To dismiss from employment. 

  • To release from one's grasp; to go from a state of holding on to a state of no longer holding on. 

  • To emotionally disengage or to distract oneself from a situation. 

  • To fail to maintain a standard of appearance, behavior, or performance. 

  • Used other than figuratively or idiomatically: see let, go. 

  • To gain weight 

rein

verb
  • To restrain; to control; to check. 

  • To obey directions given with the reins. 

  • To direct or stop a horse by using reins. 

noun
  • A strap or rope attached to a bridle or bit, used to control a horse, animal or young child. 

  • The inward impulses; the affections and passions, formerly supposed to be located in the area of the kidneys. 

  • An instrument or means of curbing, restraining, or governing. 

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