Finally, the Physiocrats believed that landed proprietorship was simply the direct outcome of “personal property,” or of the right of every man to provide for his own sustenance. This right includes the right of personal estate, which in turn involves the right of landed property. These three kinds of property are so closely connected that in reality they form one unit, and no one of the three can be detached without involving the destruction of the other two.[52] They were full of veneration for property of every description—not merely for landed property. “The safety of private property is the real basis of the economic order of society,” says Quesnay.[53] Mercier de la Rivière writes: “Property may be regarded as a tree of which social institutions are branches growing out of the trunk.”[54] We shall encounter this cult of property even during the terrible days of the French Revolution and the Reign of Terror. When all respect for human life was quite lost there still remained this respect for property. The defence of private property was already well-nigh complete.[55] But if they were strong in their defence of the institution they did not fail to impose upon it some onerous duties—which counterbalanced its eminent dignity. Of course, every proprietor should always be guided by reason and be mannerly in his behaviour, and he should never allow mere authority to become the rule of life.[56] Their duties are as follows: 1. They must continue without fail to bring lands into cultivation, _i.e._ they must continue the _avances foncières_.[57] 2. They must dispose of the wealth which the nation has produced in such a way as to further the general interest; this is their task as the stewards of society.[58] 3. They must aim during their leisure at giving to society all those gratuitous services which they can render, and which society so sorely needs. 4. They must bear the whole burden of taxation.