(1) The critical investigation of authorship has often taught us the _general_ conditions under which the author operated. It is probable that some of these influenced each one of the operations. We ought therefore to begin by studying the information we possess about the author and the composition of the document, taking particular pains to look in the habits, sentiments, and personal situation of the author, or in the circumstances in which he composed, for all the reasons which could have existed for incorrectness on the one hand, or exceptional accuracy on the other. In order to perceive these reasons it is necessary to be on the lookout for them beforehand. The only method, therefore, is to draw up a general set of questions having reference to the possible causes of inaccuracy. We shall then apply it to the general conditions under which the document was composed, in order to discover those causes which may have rendered the author's mental operations incorrect and vitiated the results. But all that we shall thus obtain--even in the exceptionally favourable cases in which the conditions of origin are well known--will be _general_ indications, which will be insufficient for the purposes of criticism, for criticism must always deal with each separate statement. (2) The criticism of particular statements is confined to the use of a single method, which, by a curious paradox, is the study of the _universal_ conditions under which documents are composed. The information which is not furnished by the general study of the author may be sought for by a consideration of the necessary processes of the human mind; for, since these are universal, they must appear in each particular case. We know what are the cases in which men in general are inclined to alter or distort facts. What we have to do in the case of each statement is to examine whether it was made under such circumstances as to lead us to suspect, from our knowledge of the habits of normal humanity, that the operations implied in the making of it were incorrectly performed. The practical procedure will be to draw up a set of questions relating to the habitual causes of inaccuracy. The whole of criticism thus reduces to the drawing up and answering of two sets of questions: one for the purpose of bringing before our minds those general conditions affecting the composition of the document, from which we may deduce general motives for distrust or confidence; the other for the purpose of realising the special conditions of each statement, from which special motives may be drawn for distrust or confidence. These two sets of questions ought to be drawn up beforehand in such a form as may enable us to examine methodically both the document in general and each statement in particular; and as they are the same for all documents, it is useful to formulate them once for all.