and this form is dictated beforehand by some one unacquainted with the facts. It is therefore necessary to apply a special criticism to every statement obtained by interrogation; we must ask what was the question put, and what were the preconceptions to which it may have given rise in the mind of the person interrogated.
(2) The author was badly situated for observing. The practice of the sciences teaches us what are the conditions for correct observation. The observer ought to be placed where he can see correctly, and should have no practical interest, no desire to obtain a particular result, no preconceived idea about the result. He ought to record the observation immediately, in a precise system of notation; he ought to give a precise indication of his method. These conditions, which are insisted on in the sciences of observation, are never completely fulfilled by the authors of documents.
It would be useless, therefore, to ask whether there have been chances of inaccuracy; there always have been, and it is just this that distinguishes a document from an observation. It only remains to look for the obvious causes of error in the conditions of observation: to inquire whether the observer was in a place where he could not see or hear well, as would be the case, for example, with a subordinate who should presume to narrate the secret deliberations of a council of dignitaries; whether his attention was greatly distracted by the necessity for action, as it would be on the field of battle, for example; whether he was inattentive because the facts had little interest for him; whether he lacked the special experience or general intelligence necessary for understanding the facts; whether he