Egoism is a purely relative and factitious feeling, which arises in the state of society, leads each individual to make more of himself than of any other, causes all the mutual damage men inflict one on another, and is the real source of the "sense of honour."
 Jean-Jacques Rousseau, Discourse on the Origin of Inequality Among Men (1755). copy citation

add
Author Jean-Jacques Rousseau
Source Discourse on the Origin of Inequality Among Men
Topic egoism society
Date 1755
Language English
Reference
Note Translated by G. D. H. Cole
Weblink https://en.wikisource.org/wiki/Discourse_on_the_Origin_of_Inequality_Amo...

Context

“for they differ both in themselves and in their effects. Self-respect is a natural feeling which leads every animal to look to its own preservation, and which, guided in man by reason and modified by compassion, creates humanity and virtue. Egoism is a purely relative and factitious feeling, which arises in the state of society, leads each individual to make more of himself than of any other, causes all the mutual damage men inflict one on another, and is the real source of the "sense of honour." This being understood, I maintain that, in our primitive condition, in the true state of nature, egoism did not exist; for as each man regarded himself as the only observer of his actions, the only being in the universe who took any interest in him, and the sole judge of his deserts, no feeling arising from comparisons he could not be led to make could take root in his soul;” source