Nor was this the most levelling of Turgot's arguments. He pointed out that though originally the exemption from taxation, which the nobility enjoyed, might have been defended on the ground that the nobles were bound to yield military service without pay, such service had long ceased to be performed, while on the contrary titles could be bought for money. Hence every wealthy man became a noble when he pleased, and thus exemption from taxation had come to present the line of cleavage between the rich and poor. By this thrust the privileged classes felt themselves wounded in their vitals, and the Parliament of Paris, the essence of privilege, assumed their defence. To be binding, the edicts had to be registered by the Parliament among the laws of France, and Parliament declined to make registration on the ground that the edicts were unconstitutional, as subversive of the monarchy and of the principle of order. The opinion of the court was long, but a single paragraph gives its purport: "The first rule of justice is to preserve to every one what belongs to him: this rule consists, not only in preserving the rights of property, but still more in preserving those belonging to the person, which arise from the prerogative of birth and of position.... From this rule of law and equity it follows that every system which, under an appearance of humanity and beneficence, would tend to establish between men an equality of duties, and to destroy necessary distinctions, would soon lead to disorder (the inevitable result of equality), and would bring about the overturn of civil society." This judicial opinion was an enunciation of the archaic law of caste as opposed to the modern law of equality, and the cataclysm of the French Revolution hinged upon the incapacity of the French aristocracy to understand that the environment, which had once made caste a necessity, had yielded to another which made caste an impossibility. In vain Turgot and his contemporaries of the industrial type, represented in England by Adam Smith or even by the younger Pitt, explained that unless taxes were equalized and movement accelerated, insolvency must supervene, and that a violent readjustment must follow upon insolvency. With their eyes open to the consequences, the Nobility and Clergy elected to risk revolt, because they did not believe that revolt could prevail against them. Nothing is so impressive in the mighty convulsion which ensued as the mental opacity of the privileged orders, which caused them to increase their pressure in proportion as resistance increased, until finally those who were destined to replace them reorganized the courts, that they might have an instrument wherewith to slaughter a whole race down to the women and children. No less drastic method would serve to temper the rigidity of the aristocratic mind. The phenomenon well repays an hour of study.