Thomas Hobbes wrote Leviathan over several years with it first being published in 1651. Hobbes is probably best known for describing the natural state of man as "all against all".

The all against all is described in several places in Leviathan, but is used to determine the necessity for the 'Commonwealth' as a form of state to stop man having to use violence to protect their freedom.

The final cause, end, or design of men (who naturally love liberty, and dominion over others) in the introduction of that restraint upon themselves, in which we see them live in Commonwealths, is the foresight of their own preservation, and of a more contented life thereby; that is to say, of getting themselves out from that miserable condition of war which is necessarily consequent, as hath been shown, to the natural passions of men when there is no visible power to keep them in awe, and tie them by fear of punishment to the performance of their covenants, and observation of those laws of nature set down in the fourteenth and fifteenth chapters.

It is important to note that to Hobbes the sovereign power keeps man in check through 'awe' rather than through the individual's reasoning that they will be better off under such a system. This is probably a sign of the times for when Hobbes was writing this the idea of a divine right to rule under a monarch was still the dominant political philosophy.

Hobbes' book in large part excuses the necessity of unitary power in a monarch in order to stave off all against all violence; but also civil war between a divided kingdom. The sovereign power must be unitary or the result - civil war - is as bad as individuals in an all against all state of violence. I suspect Iraqis won't quibble with the definition.

However Hobbes writes from a pro-state point of view and he describes, amusingly for the modern political reader, the rights of the state. He constantly appeals to the states having a right to do so-and-so. Considering the modern view that rights are the just basis for the relationship between individual and government; ie granted by the individual, then it is a pre-modern view of politics and not just because of the use of the monarch as executive.