in language which does not permit us to represent them in our minds with exactness, form the data of history. The historian, however, is obliged to picture the facts in his imagination, and he should make it his constant endeavour to construct his mental images out of none but correct elements, so that he may imagine the facts as he would have seen them if he had been able to observe them personally. But the formation of a mental image requires more elements than the documents supply. Let any one endeavour to form a mental representation of a battle or a ceremony out of the data of a narrative, however detailed; he will see how many features he is compelled to add. This necessity becomes physically perceptible in attempts to restore monuments in accordance with descriptions (for example, the Temple at Jerusalem), in pictures which claim to be representations of historical scenes, in the drawings of illustrated newspapers.
Every historical image contains a large part of fancy. The historian cannot get rid of it, but he can take stock of the real elements which enter into his images and confine his constructions to these; they are the elements which he has derived from the documents. If, in order to understand the battle between Cæsar and Ariovistus, he finds it necessary to make a mental picture of the two opposing armies, he will be careful to draw no conclusions from the general aspect under which he imagines them; he will base his reasonings exclusively on the real details furnished by the documents.
V. The problem of historical method may be finally stated as follows. Out of the different elements we find in documents we form mental images. Some