Proof beyond reasonable doubt has not been defined. Prof. Wigmore in his classic Treatise on Evidence highlights the difficulties in ascertaining how convinced one must be to become convinced beyond a reasonable doubt. He says that “the truth is that no one has invented or discovered a mode of measurement for the intensity of human belief. Hence, there can be as yet no successful method of communicating intelligibly a sound method of self-analysis for one’s belief. And yet the choice of the standard of proof makes the difference.” The standard that must be met by the prosecution's evidence in a criminal prosecution: that no other logical explanation can be derived from the facts except that the defendant committed the crime, thereby overcoming the presumption that a person is innocent until proven guilty.