involve vs let go

involve

verb
  • To cause or engage (someone or something) to participate or to become connected or implicated. 

  • To take in; to gather in; to mingle, blend or merge. 

  • To comprise or include; to have as a related part. 

  • To complicate or make intricate. 

  • To envelop, enfold, entangle. 

let go

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

  • 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 ignore (a comment, etc.). 

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

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

  • To gain weight 

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