soul-searching vs speculation

soul-searching

noun
  • Probing introspection; a critical consideration of one's conscience; also, an instance of such consideration. 

adj
  • Involving probing introspection, or a critical consideration of one's conscience, especially motives and values. 

speculation

noun
  • The process of thinking or meditating on a subject. 

  • The act or process of reasoning a priori from premises given or assumed. 

  • An investment involving higher-than-normal risk in order to obtain a higher-than-normal return. 

  • A conclusion to which the mind comes by speculating; mere theory; notion; conjecture. 

  • The act or practice of buying land, goods, shares, etc., in expectation of selling at a higher price, or of selling with the expectation of repurchasing at a lower price; a trading on anticipated fluctuations in price, as distinguished from trading in which the profit expected is the difference between the retail and wholesale prices, or the difference of price in different markets. 

  • A card game in which the players buy from one another trumps or whole hands, upon a chance of getting the highest trump dealt, which entitles the holder to the pool of stakes. 

  • The process of anticipating which branch of code will be chosen and executing it in advance. 

How often have the words soul-searching and speculation occurred in a corpus of books? (source: Google Ngram Viewer )