II. In every science the next step after observing the facts is to formulate a series of questions according to some methodical system;[179] every science is composed of the answers to such a series of questions. In all the sciences of direct observation, even if the questions to be answered have not been put down in advance, the facts which are observed suggest questions, and require them to be formulated precisely. But historians have no discipline of this kind; many of them are accustomed to imitate artists, and do not even think of asking themselves what they are looking for. They take from their documents those parts which strike them, often for purely personal reasons, and reproduce them, changing the language and adding any miscellaneous reflections which come into their minds. If history is not to be lost in the confusion of its materials, it must be made a rule to proceed here, as in the other sciences, by way of question and answer.[180] But how are the questions to be chosen in a science so different from the others? This is the fundamental problem of method. The only way to solve it is to begin by determining the essential characteristic of historical facts by which they are differentiated from the facts of the other sciences. The sciences of direct observation deal with _realities_, taken in their entirety. The science which borders most closely on history in respect of its subject-matter, descriptive zoology, proceeds by the examination of a real and complete animal. This animal is first observed, as a whole, by actual vision; it is then dissected into its parts; this dissection is _analysis_ in the original sense of the word ([Greek: hanalhyein], to break up into parts). It is then possible to put the parts together again in such a way as to exhibit the structure of the whole; this is _real_ synthesis. It is possible to watch the _real_ movements which are the functions of the organs in such a way as to observe the mutual actions and reactions of the different parts of the organism. It is possible to compare _real_ wholes and see what are the parts in which they resemble each other, so as to be able to classify them according to real points of resemblance. The science is a body of objective knowledge founded on _real_ analysis, synthesis, and comparison; actual sight of the things studied guides the scientific researcher and dictates the questions he is to ask himself.