principle vs virtue

principle

noun
  • Moral rule or aspect. 

  • A fundamental essence, particularly one producing a given quality. 

  • A rule used to choose among solutions to a problem. 

  • A rule or law of nature, or the basic idea on how the laws of nature are applied. 

  • Bernoulli's Principle 

  • An original faculty or endowment. 

  • A fundamental assumption or guiding belief. 

  • A source, or origin; that from which anything proceeds; fundamental substance or energy; primordial substance; ultimate element, or cause. 

verb
  • To equip with principles; to establish, or fix, in certain principles; to impress with any tenet or rule of conduct. 

virtue

noun
  • Accordance with moral principles; conformity of behaviour or thought with the strictures of morality; good moral conduct. 

  • A creature embodying divine power, specifically one of the orders of heavenly beings, traditionally ranked above angels and below archangels. 

  • A particular manifestation of moral excellence in a person; an admirable quality. 

  • Specifically, each of several qualities held to be particularly important, including the four cardinal virtues, the three theological virtues, or the seven virtues opposed to the seven deadly sins. 

  • An inherently advantageous or excellent quality of something or someone; a favourable point, an advantage. 

  • Specifically, moral conduct in sexual behaviour, especially of women; chastity. 

  • The inherent power or efficacy of something (now only in phrases). 

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