But when you draw thence a comparison to moral relations, I own that I am altogether at a loss to understand you.

A moral action, a crime, such as ingratitude, is a complicated object.

Does the morality consist in the relation of its parts to each other?
How?
After what manner?
Specify the relation: be more particular and explicit in your propositions, and you will easily see their falsehood.
No, say you, the morality consists in the relation of actions to the rule of right; and they are denominated good or ill, according as they agree or disagree with it.

What then is this rule of right?
In what does it consist?
How is it determined?
By reason, you say, which examines the moral relations of actions.

So that moral relations are determined by the comparison of action to a rule.