lecture vs let go

lecture

verb
  • To preach, to berate, to scold. 

  • To teach (somebody) by giving a speech on a given topic. 

noun
  • a class that primarily consists of a (weekly or other regularly held) lecture (as in sense 1) 

  • A berating or scolding. 

  • A spoken lesson or exposition, usually delivered to a group. 

let go

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

  • 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 emotionally disengage or to distract oneself from a situation. 

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

  • To gain weight 

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