document worked: this author is, in such a case, a mere agent of transmission; the true author is the person who supplied him the information. The critic, therefore, must change his ground, and ask whether the informant observed and reported correctly; and if he too had the information from some one else (the commonest case), the chase must be pursued from one intermediary to another, till the person is found who first launched the statement on its career, and with regard to him the question must be asked: Was he an accurate observer?
Logically such a search is not inconceivable; ancient collections of Arab traditions give lists of their successive guarantors. But, in practice, lack of documents nearly always prevents us from getting as far as the observer of a fact; the observation remains anonymous. A general question then presents itself: How are we to criticise an anonymous statement? It is not only "anonymous documents" with which we are concerned, where the composition as a whole is the work of an unknown author; even when the author is known, this question arises with respect to each statement of his drawn from an unknown source.
Criticism works by reproducing the conditions under which an author wrote, and has hardly anything to take hold of where a statement is anonymous. The only method left is to examine the general conditions of the document. We may inquire whether there is any feature common to all the statements of a document indicating that they all proceed from persons having the same prejudices or passions: in this case the tradition followed by the author is biassed; the tradition followed by Herodotus has both an Athenian bias and a Delphic bias. In