So that in the nature of man we find three principal causes of quarrel.
First, competition; secondly, diffidence; thirdly, glory.  

  The first maketh man invade for gain; the second, for safety; and the
third, for reputation. The first use violence, to make themselves masters of
other men’s 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. For ‘war’
consisteth not in battle only or the act of fighting, but in a tract of time
wherein the will to contend by battle is sufficiently known, and therefore
the notion of ‘time’ is to be considered in the nature of war, as it is in
the nature of weather. For as the nature of foul weather lieth not in a
shower or two of rain but in an inclination thereto of many days together,
so the nature of war consisteth not in actual fighting but in the known
disposition thereto during all the time there is no assurance to the
contrary. All other time is ‘peace.’  

  Whatsoever therefore is consequent to a time or war where every man is
enemy to every man, the same is consequent to the time wherein men live
without other security than what their own strength and their own invention
shall furnish them withal. In such condition there is no place for industry,
because the fruit thereof is uncertain, and consequently no culture of the
earth, no navigation nor use of the commodities that may be imported by sea,
no commodious building, no instruments of moving and removing such things as
require much force, no knowledge of the face of the earth; no account of
time, no arts, no letters, no society, and, which is worst of all, continual
fear and danger of violent death, and the life of man solitary, poor, nasty,
brutish, and short. 

                           Thomas Hobbes