Sometimes a new moral or political entity is created rather by immediate insight than by the slow process of deliberate analysis. Some seer of genius perceives in a flash the essential likeness of things hitherto kept apart in men's minds--the impulse which leads to anger with one's brother, and that which leads to murder, the charity of the widow's mite and of the rich man's gold, the intemperance of the debauchee and of the party leader. But when the master dies the vision too often dies with him. Plato's 'ideas' became the formulae of a system of magic, and the command of Jesus that one should give all that one had to the poor handed over one-third of the land of Europe to be the untaxed property of wealthy ecclesiastics. It is this last relation between words and things which makes the central difficulty of thought about politics. The words are so rigid, so easily personified, so associated with affection and prejudice; the things symbolised by the words are so unstable. The moralist or the teacher deals, as a Greek would say, for the most part, with 'natural,' the politician always with 'conventional' species. If one forgets the meaning of motherhood or childhood, Nature has yet made for us unmistakable mothers and children who reappear, true to type, in each generation. The chemist can make sure whether he is using a word in precisely the same sense as his predecessor by a few minutes' work in his laboratory. But in politics the thing named is always changing, may indeed disappear and may require hundreds of years to restore. Aristotle defined the word 'polity' to mean a state where 'the citizens as a body govern in accordance with the general good.'[16] As he wrote, self-government in those States from which he abstracted the idea was already withering beneath the power of Macedonia. Soon there were no such States at all, and, now that we are struggling back to Aristotle's conception, the name which he defined is borne by the 'police' of Odessa. It is no mere accident of philology that makes 'Justices' Justice' a paradox. From the time that the Roman jurisconsults resumed the work of the Greek philosophers, and by laborious question and answer built up the conception of 'natural justice, it, like all other political conceptions, was exposed to the two dangers. On the one hand, since the original effort of abstraction was in its completeness incommunicable, each generation of users of the word subtly changed its use. On the other hand, the actions and institutions of mankind, from which the conception was abstracted, were as subtly changing. Even although the manuscripts of the Roman lawyers survived, Roman law and Roman institutions had both ceased to be. When the phrases of Justinian were used by a Merovingian king or a Spanish Inquisitor not only was the meaning of the words changed, but the facts to which the words could have applied in their old sense were gone. Yet the emotional power of the bare words remained.