The degree of certainty that it is possible to attain in history varies greatly in different departments. The growth of institutions and laws, military events, changes in manners and in creeds, can be described with much confidence, and although it is more difficult to depict the inner moral life of nations, the influences that form their characters and prepare them for greatness or decay, yet when the materials for our induction are sufficiently large this field of history may be studied with great profit. Diplomatic history and the more secret springs of political history can only be fully disclosed when the archives relating to them have been explored and when the confidential correspondence of the chief actors in them has been published. The biographical element in history is always the most uncertain. Even among contemporaries the judgment of character and motives depends largely on indications so slight and subtle that they rarely pass into books and are only fully felt by direct personal contact, and the smallest knowledge of life shows how quickly anecdotes and sayings are distorted, coloured, and misplaced when they pass from lip to lip. Most of the 'good sayings' of history are invention, and most of them have been attributed to different persons. A history which is plainly written under the influence of party bias has the value of an advocate's speech giving one side of the question. When our only materials for the knowledge of a period are derived from such histories, the saying of Voltaire should be remembered--that we can confidently believe only the evil which a party writer tells of his own side and the good which he recognises in his opponents. In judging the historian we must consider his nearness to the events he relates, his probable means of information and the internal evidence in his narrative of accuracy, honesty, and judgment, and we must also consider the standard of proof and the methods of historical writing prevailing in his time. A modern writer who placed in the mouths of his personages speeches which he himself invented would be justly discredited, but in antiquity it was a recognised custom for a historian to embody in fictitious speeches the reflections suggested by his narrative and the motives which he believed to have actuated his heroes.