Certainty is so essential to a law, that a law without it cannot be just. For if the trumpet gives an uncertain sound, who shall prepare himself to the battle? So if the law has an uncertain sense, who shall obey it? A law, therefore, ought to give warning before it strikes: and it is a true maxim, that the best law leaves least to the breast of the judge, which is effected by certainty.
Francis Bacon, quoted in the Preface of Cunningham's Reports