The object of criticism is to discover what in a document may be accepted as true. Now the document is only the final result of a long series of operations, on the details of which the author gives us no information. He had to observe or collect facts, to frame sentences, to write down words; and these operations, which are perfectly distinct one from another, may not all have been performed with the same accuracy. It is therefore necessary to _analyse_ the product of the author's labour in order to distinguish which operations have been incorrectly performed, and reject their _results_. _Analysis_ is thus necessary to criticism; all criticism begins with analysis. In order to be logically complete, the analysis ought to reconstruct _all_ the operations which the author must have performed, and to examine them _one by one_, to see whether each has been performed correctly. It would be necessary to pass in review all the successive acts by which the document was produced, from the moment when the author observed the fact which is its subject up to the movements of his hand by which he traced the letters of the document; or, rather, it would be necessary to proceed in the opposite direction, step by step, from the movements of the hand back to the observation. This method would be so long and so tedious that no one would ever have the time or the patience to apply it. Internal criticism is not, like external criticism, an instrument used for the mere pleasure of using it;[130] it yields no immediate satisfaction, because it does not definitively solve any problem. It is only applied because it is necessary, and its use is restricted to a bare minimum. The most exacting historian is satisfied with an abridged method which concentrates all the operations into two groups: (1) the analysis of the contents of the document, and the positive interpretative criticism which is necessary for ascertaining what the author meant; (2) the analysis of the conditions under which the document was produced, and its negative criticism, necessary for the verification of the author's statements. This twofold division of the labour of criticism is, moreover, only employed by a select few. The natural tendency, even of historians who work methodically, is to read the text with the object of extracting information directly from it, without any thought of first ascertaining what exactly was in the author's mind.[131] This procedure is excusable at most in the case of nineteenth-century documents, written by men whose language and mode of thought are familiar to us, and then only when there is not more than one possible interpretation. It becomes dangerous as soon as the author's habits of language or thought begin to differ from those of the historian who reads him, or when the meaning of the text is not obvious and indisputable. Whoever, in reading a text, is not exclusively occupied with the effort to understand it, is sure to read impressions