Freud observes one of the most counterintuitive facts of moral psychology: the more virtuous a person becomes, the harsher their conscience. Saints experience the deepest sense of sinfulness. Those who have renounced the most feel the most guilty. This is not accidental: the superego intensifies its demands in proportion to the instinctual energy that has been turned back upon the self. Moral effort does not satisfy the superego — it emboldens it.
Freud proposes that civilization has a superego of its own — a cultural conscience embodied in its ethical systems, its laws, its religion. Like the individual superego, the cultural superego makes demands that are impossible to fully satisfy, and punishes failure with the characteristic affect of guilt. The commandment to love one's enemy is an example: a demand so far beyond instinctual possibility that its effect can only be to intensify the sense of inadequacy and guilt in those who attempt to obey it.
The deepest discontent of civilization, on this account, is not poverty or injustice or political oppression but the chronic sense of unworthiness that advanced moral development produces. The price of civilized virtue is an inescapable self-accusation — the sense that one has never done enough, renounced enough, loved enough. Progress in civilization, measured by the strengthening of conscience, is progress in guilt.
The sense of guilt is the organizing theme of Chapters VI and VII of Civilization and Its Discontents and represents Freud's most sustained engagement with moral philosophy.