bread and butter vs sustenance

bread and butter

noun
  • That which is central or fundamental, as to one's business, survival, or income; a staple or cornerstone. 

  • Used other than figuratively or idiomatically: see bread, butter. 

intj
  • Said when two people walking together are temporarily separated by an obstacle in order to indicate that they belong together. 

sustenance

noun
  • Something that provides support or nourishment. 

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