"The life of law lies not in logic, but in experience", which is a famous saying of American Justice Holmes. 1880 is introduced in the common law and should belong to the common law system. While emphasizing the importance of logical methods and forms, he also pointed out that although logical methods and forms satisfy the pursuit of certainty and harmony rooted in everyone's mind, certainty is often just an illusion, and there are competing judgments on the value and importance of various legislative reasons behind logical forms, which are often vague and unconscious judgments.