Now, what have we a right to possess?
That which is required for our labor and consumption; Cicero's comparison of the earth to a theatre proves it.

According to that, each one may take what place he will, may beautify and adorn it, if he can; it is allowable: but he must never allow himself to overstep the limit which separates him from another.

The doctrine of Cicero leads directly to equality; for, occupation being pure toleration, if the toleration is mutual (and it cannot be otherwise) the possessions are equal.
Grotius rushes into history; but what kind of reasoning is that which seeks the origin of a right, said to be natural, elsewhere than in Nature?
This is the method of the ancients: the fact exists, then it is necessary, then it is just, then its antecedents are just also.
Nevertheless, let us look into it.
"Originally, all things were common and undivided; they were the property of all." Let us go no farther.

Grotius tells us how this original communism came to an end through ambition and cupidity; how the age of gold was followed by the age of iron, &c.

So that property rested first on war and conquest, then on treaties and agreements.