Whilst Dorian oligarchs and Macedonian kings crushed the liberties of Greece, the Roman Republic was ruined, not by its enemies, for there was no enemy it did not conquer, but by its own vices. It was free from many causes of instability and dissolution that were active in Greece--the eager quickness, the philosophic thought, the independent belief, the pursuit of unsubstantial grace and beauty. It was protected by many subtle contrivances against the sovereignty of numbers and against legislation by surprise. Constitutional battles had to be fought over and over again; and progress was so slow, that reforms were often voted many years before they could be carried into effect. The authority allowed to fathers, to masters, to creditors, was as incompatible with the spirit of freedom as the practice of the servile East. The Roman citizen revelled in the luxury of power; and his jealous dread of every change that might impair its enjoyment portended a gloomy oligarchy. The cause which transformed the domination of rigid and exclusive patricians into the model Republic, and which out of the decomposed Republic built up the archetype of all despotism, was the fact that the Roman Commonwealth consisted of two States in one. The constitution was made up of compromises between independent bodies, and the obligation of observing contracts was the standing security for freedom. The plebs obtained self-government and an equal sovereignty, by the aid of the tribunes of the people, the peculiar, salient, and decisive invention of Roman statecraft. The powers conferred on the tribunes, that they might be the guardians of the weak, were ill defined, but practically were irresistible. They could not govern, but they could arrest all government. The first and the last step of plebeian progress was gained neither by violence nor persuasion, but by seceding; and, in like manner, the tribunes overcame all the authorities of the State by the weapon of obstruction. It was by stopping public business for five years that Licinius established democratic equality. The safeguard against abuse was the right of each tribune to veto the acts of his colleagues. As they were independent of their electors, and as there could hardly fail to be one wise and honest man among the ten, this was the most effective instrument for the defence of minorities ever devised by man. After the Hortensian law, which in the year 286 gave to the plebeian assembly co-ordinate legislative authority, the tribunes ceased to represent the cause of a minority, and their work was done.