tematic arrangement of the various interrelations continually surrounds the final truths of the last instance with a prolific and spreading growth of hypotheses. Look at the long succession of progressive steps from Galen to Malpighi necessary to establish correctly so simple a thing as the circulation of the blood of mammals, yet how little we know of the origin of blood corpuscles and how many mistakes we make in, for example, rationally connecting the symptoms and cause of a disease. Besides there are frequently discoveries like those of the cell which compel us to entirely revise all hitherto firmly established truth of the last instance in biology, and to lay numbers of such truths aside for good and all. He who would therefore in this science undertake the proclamation of absolute and immutable truths must be content with such platitudes as the following: "All men must die; all female mammals have mammary glands, etc." He will not even be able to say that the greater animals digest their food by means of the stomach and bowels and not with the head because the centralised system of nerves in the head is not adapted to digestion.
But things are worse with regard to final truths of last instance in the third group of sciences—the historical. These are concerned with the conditions of human life, social conditions, forms of law and the state with their idealistic superstructure of philosophy, religion, art, etc., in their historic succession and in their present day manifestations. In organic nature we have at least to do with a succession of regular phenomena which regularly repeat themselves as far as our immediate observation goes, within very wide limits. Organic species have remained on the whole unaltered since the time of Aristotle. In social history, on the other hand, repetitions of conditions are the exception, not the rule,
