ABSTRACT
We can decide which advantages we wish our present worldwide society to ensure and which ends we wish it to promote. An understanding of the workings of international societies in the past helps us to translate our wishes realistically into practice, by showing us what modifications of our present international society are practicable, what advantages they might bring and at what price. A realistic understanding is very difficult to obtain if we remain imprisoned in the conventional legitimacies and half-conscious assumptions of our own time. We need a broader base of comparison. As the natural sciences and medicine look for many examples of a phenomenon in order to understand it well enough to modify it, so history can enable us to distinguish the area of necessity from the area of choice.
