There is a danger that, in insisting on the primarily moral causation of the process of social disease and decay, we may on the one hand relapse into a delusive sense of moral superiority, and on the other hand fail to realise how the subjective moral divagation becomes politically effectual in structural and economic change. It is the understood process of causation that is alone truly instructive. But the instruction is deepened in the ratio of our realisation of the decay. Though it is clear that before Rome many a civilisation had gone to violent wreck, there is in recorded history no more overwhelming memory of long triumph and long downfall than that "from the far-distant morning when a small clan of peasants and shepherds felled the forests on the Palatine to raise altars to its tribal deities, down to the tragic hour in which the sun of Græco-Latin civilisation set over the deserted fields, the abandoned cities, the homeless, ignorant, and brutalised peoples of Latin Europe."[440] And this whole tremendous arc of triumph and decline is to be understood as the historic expression of the specially conditioned bias of conquest in one people. The decline is the due sequence of the "rise": everything roots in the wrong relation of communities throughout the Empire. The extension of such a social disease as slavery is one of the symptoms, one of the sequelæ, of the central malady.[441] A totally progressive State eliminates or minimises slavery; a declining one fails to do so. The economic malady involved affects primarily the dominant or parasitic State or central part, its condition of parasitism being more deadly than its draining effect on the others. _Their_ malady lay in their state of subjugation, which was an impoverishment of character and political faculty; and thus it came about that the collapse of the centre of organisation meant the fall of the entire civilisation of Western Europe before the new barbarism. Rome had so visibly ruined all that we are apt to forget how the process of moral and political retrogression had begun in the Greek world long before. There, however, the Roman conquest was but a consummation; and the economic and political continuance of the Eastern Empire was concurrent with a moral and intellectual contraction which was never recovered from. In a word, varying conditions determined the differences of continuance and evolution in the two spheres. But the causation is none the less clear throughout.