Everywhere inequality is a cause of revolution, but an inequality in which there is no proportion- for instance, a perpetual monarchy among equals; and always it is the desire of equality which rises in rebellion.
 Aristotle, Politics (4th century BC). copy citation

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Author Aristotle
Source Politics
Topic rebellion inequality
Date 4th century BC
Language English
Reference
Note Translated by Benjamin Jowett
Weblink http://classics.mit.edu/Aristotle/politics.html

Context

“but to this day the magistrates are the only members of the ruling class who are compelled to go to the Heliaea when an election takes place, and the office of the single archon was another oligarchical feature. Everywhere inequality is a cause of revolution, but an inequality in which there is no proportion- for instance, a perpetual monarchy among equals; and always it is the desire of equality which rises in rebellion. Now equality is of two kinds, numerical and proportional; by the first I mean sameness or equality in number or size; by the second, equality of ratios. For example, the excess of three over two is numerically equal to the excess of two over one;” source