The only justified demand which could be met was that a system of division and classification should be proposed which should give fair play to every existing scientific tendency. The minimum of classification was to be combined with the maximum of freedom, and to secure that a careful consideration of principles was indeed necessary. To bring logical order into the sciences which stand out clearly with traditional rights is not difficult; but the chances are too great that certain tendencies of thought might fail to find recognition or might be suppressed by scientific prejudice. Any serious omission would indeed have necessarily inhibited the freedom of expression. To secure thus the greatest inner fullness of the programme, seemed indeed the most important task in the elaboration of the ground-plan. The fears that we might offer empty generalization instead of scholarly facts, or that we might simply heap up encyclopedic information instead of gaining wide perspectives, or that we might interfere with the living connections of sciences by the logical demarcation lines, or that we might disturb the scholar in his freedom by determining beforehand his place in the classification,--all these fears and objections, which were repeatedly raised when the plan was first proposed, seemed indeed unimportant compared with the fear that the programme might be unable to include all scientific tendencies of the time. That would have been, indeed, the one fundamental mistake, as the whole Congress work was planned in the service of the great synthetic movement which pervades the intellectual life of to-day. The undertaking would be useless and even hindering if it were not just the newer and deeper tendencies that came to most complete expression in it. Everything depended, therefore, upon the fullest possible representation of scientific endeavors in the plan. But no one can become aware of this manifoldness and of the logical relations who does not go back to the ultimate principles of the human search for truth. We have, therefore, to enter now into a full discussion of the principles which have controlled the classification and subdivision of the whole work. The discussion is necessarily in its essence a philosophical one, as it was earlier made plain that philosophy must lay out the plan, while in the realization of the plan through concrete work the scientist alone, and not the logician, has to speak. Yet here again it may be said that while our discussion of principles in its essence is logical, in another respect it is a merely historical account. The question is not what principles of classification are to be acknowledged as valuable now that the work of the Congress lies behind us, but what principles were accepted and really led to the organization of the work in that form in which it presents itself in the records of the following volumes. II THE CLASSIFICATION OF THE SCIENCES 1. _The Development of Classification_