Thomas Hobbes, from The Leviathan
From this equality of ability, arises equality of hope in the attaining of our ends. And therefore if any two men desire the same thing, which nevertheless they cannot both enjoy, they become enemies; and in the way to their end, which is principally their own conservation, and sometimes their delectation only, endeavour to destroy or subdue one another. And from hence it comes to pass, that where an invader has no more to fear than another manís single power; if one plant, sow, build, or possess a convenient seat, others may probably be expected to come prepared with forces united, to dispossess and deprive him, not only of the fruit of his labour, but also of his life or liberty. And the invader again is in the like danger of another.
And from this diffidence of one another, there is no way for any man to secure himself, so reasonable, as anticipation; that is, by force, or wiles, to master the persons of all men he can, so long, till he see no other power great enough to endanger him: and this is no more than his own conservation requires, and is generally allowed. Also because there be some, that taking pleasure in contemplating their own power in the acts of conquest, which they pursue farther than their security requires; if others, that otherwise would be glad to be at least within modest bounds, should not by invasion increase their power, they would not be able, long time, by standing only on their defence, to subsist. And by consequence, such augmentation of dominion over men being necessary to a manís conservation, it ought to be allowed him.
Again, men have no pleasure, but on the contrary, a great deal of grief, in keeping company, where there is no power able to overawe them all. For every man looks for his companion to value him, at the same rate he sets upon himself and upon all signs of contempt, or undervaluing, naturally endeavours, as far as he dares (which among them that have no common power to keep them in quiet, is far enough to make them destroy each other), to extort a greater value from his contemners, by damage; and from others, by the example.
So that in the nature of man we find three principal causes of quarrel. First, competition; second, diffidence; thirdly, glory.
The first makes men invade for gain; the second, for safety; and the third, for reputation. The first use violence, to make themselves masters of other menís persons, wives, children, and cattle; the second, to defend them; the third, for trifles, as a word, a smile, a different opinion, and any other sign of undervalue, either direct in their persons, or by reflection in their kindred, their friends, their nation, their profession, or their name.
Hereby it is manifest, that during the time men live without a common power to keep them all in awe, they are in that condition which is called war; and such a war, as is of every man, against every man.