linchpin vs motive

linchpin

noun
  • A central cohesive source of stability and security; a person or thing that is critical to a system or organisation. 

  • A pin inserted through holes at the end of an axle or shaft, so as to secure a wheel or shaft-mounted device. 

verb
  • To adopt as, or serve as, a central cohesive source of stability and security. 

motive

noun
  • A motif. 

  • A motif; a theme or subject, especially one that is central to the work or often repeated. 

  • An incentive to act in a particular way; a reason or emotion that makes one want to do something; anything that prompts a choice of action. 

  • Something which causes someone to want to commit a crime; a reason for criminal behaviour. 

adj
  • Relating to motion and/or to its cause 

  • Causing motion; having power to move, or tending to move 

verb
  • To prompt or incite by a motive or motives; to move. 

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