Selection from –Political Treatise - Chapter III, of the right of supreme authorities (Page 5)

Spinoza's Words – (conclusion of Chapter III - on the relations of one commonwealth to another)

After explaining the right of supreme authorities over citizens and the duty of subjects, it remains to consider the right of such authorities against the world at large.

The right of the supreme authorities is nothing else but simple natural right, it follows that two dominions stand towards each other in the same relation as do two men in the state of nature, with this exception, that a commonwealth can provide against being oppressed by another; which a man in the state of nature cannot do.

A commonwealth then is so far independent, as it can plan and provide against oppression by another and so far dependent on another commonwealth, as it fears that other's power, or is hindered by it from executing its own wishes, or lastly, as it needs its help for its own preservation or increase.

Spinoza goes on to explain that commonwealths can help each other and form "contracting powers" which they may dissolve when the situation changes and a gain no longer exists