idler vs self-starter

idler

noun
  • One who idles; one who spends his or her time in inaction. 

  • One who idles; a lazy person; a sluggard. 

  • A mechanical device such as a pulley or wheel that does not transmit power, but supports a moving belt etc. 

self-starter

noun
  • A person who shows initiative and resourcefulness. 

  • A mechanism (usually one operated by electricity, compressed air, a spring, or an explosive gas), attached to an internal-combustion engine, as on an automobile, and used as a means of starting the engine without cranking it by hand. 

How often have the words idler and self-starter occurred in a corpus of books? (source: Google Ngram Viewer )