lawful or unlawful, according as he thinks it will bring him profit or loss:
vanity leads him to despise his equals, and refuse their guidance: envy of
superior fame or fortune (for such gifts are never equally distributed)
leads him to desire and rejoice in his neighbour's downfall. (20) I need
not go through the whole list, everyone knows already how much crime.
results from disgust at the present - desire for change, headlong anger,
and contempt for poverty - and how men's minds are engrossed and kept
in turmoil thereby.

(17:21) To guard against all these evils, and form a dominion where no room
is left for deceit; to frame our institutions so that every man, whatever
his disposition, may prefer public right to private advantage, this is the
task and this the toil. (22) Necessity is often the mother of invention, but
she has never yet succeeded in framing a dominion that was in less danger
from its own citizens than from open enemies, or whose rulers did not fear
the latter less than the former. (23) Witness the state of Rome, invincible
by her enemies, but many times conquered and sorely oppressed by her own
citizens, especially in the war between Vespasian and Vitellius. (24) (See
Tacitus, Hist. bk. iv. for a description of the pitiable state of the city.)

(17:25) Alexander thought prestige abroad more easy to acquire than prestige
at home, and believed that his greatness could be destroyed by his own
followers. (26) Fearing such a disaster, he thus addressed his friends:
"Keep me safe from internal treachery and domestic plots, and I will front
without fear the dangers of battle and of war. (27) Philip was more secure
in the battle array than in the theatre: he often escaped from the hands of
the enemy, he could not escape from his own subjects. (28) If you think over
the deaths of kings, you will count up more who have died by the assassin
than by the open foe." (Q. Curtius, chap. vi.)