Having thus justified the scope of the present book and indicated the general lines on which its task should be carried out, a few words must be devoted to the method of dealing with the evidence. We start our investigations with (1) the Australian first-hand information, and (2) a general idea of the object of our research, that is a general idea of the individual family. This implies that during the process of research these two sets of data must be checked against each other. On the one hand we must continually extract from the evidence all that corresponds to our general idea of the individual family; on the other hand this idea must be specialized and determined according to the evidence. It is clear enough what, broadly speaking, is meant by the Individual Family. But what exactly will be the features of this institution in Australia, that must be extracted from the evidence. This evidence is, on the other hand, given in the majority of cases in a very crude state, without reference to any theoretical points of view. The facts are often given in a purely casual and colloquial way. It is part of the task to sift out each one of them, and to ask if it can have any bearing on the present subject. Many facts that seemed not to bear immediately on it, yet furnished some very useful inferences. In short, the first duty of such a work as the present is to ask from the evidence right questions in the right way. But even if a certain point has been settled upon as essentially important to be inquired into, and information referring to it has been gathered, the task is not yet finished. The statements collected on this point will as a rule present more or less radical discrepancies. After we have heard twenty opinions on the same subject which by no means agree with each other, to which shall we adhere? A method of dealing with evidence must be fixed upon. In the first place the statements are of the most heterogeneous character and value. They must be submitted to some criticism before use can be made of them. After the degree of their reliability has been settled, and after, by a criticism of each statement, some of the contradictions have been removed, it must be considered how far the differences between the statements may be regarded as due to irreducible, local variations of the given institution; in other words, the problem must be discussed from the geographical standpoint. Finally a certain system of weighing the evidence must be chosen, so as to draw from it the most correct conclusions, and never to prove too much or too little. So there are three different processes: criticism, localization of differences, and drawing of conclusions; all of which must be done according to a careful and conscientious method.