the better should be more loved than he loves, and so should the more useful, and similarly in each of the other cases; for when the love is in proportion to the merit of the parties, then in a sense arises equality, which is certainly held to be characteristic of friendship.
But equality does not seem to take the same form in acts of justice and in friendship
 Aristotle, Nicomachean Ethics (c. 334 BC - 330 BC). copy citation

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Author Aristotle
Source Nicomachean Ethics
Topic friendship equality
Date c. 334 BC - 330 BC
Language English
Reference
Note Translated by W. D. Ross
Weblink http://classics.mit.edu/Aristotle/nicomachaen.mb.txt

Context

“but when children render to parents what they ought to render to those who brought them into the world, and parents render what they should to their children, the friendship of such persons will be abiding and excellent. In all friendships implying inequality the love also should be proportional, i.e. the better should be more loved than he loves, and so should the more useful, and similarly in each of the other cases; for when the love is in proportion to the merit of the parties, then in a sense arises equality, which is certainly held to be characteristic of friendship. But equality does not seem to take the same form in acts of justice and in friendship; for in acts of justice what is equal in the primary sense is that which is in proportion to merit, while quantitative equality is secondary, but in friendship quantitative equality is primary and proportion to merit secondary.” source