Under the law of reason nothing takes place without a cause, any more than under the law of nature.
Gist of Idea
Both nature and reason require that everything has a cause
Jean-Jacques Rousseau (The Social Contract (tr Cress) , II.04)
Is this the influence of Leibniz? Note that the principle is identified in two different areas, so in nature we may say 'everything has a cause', and in rationality we may say 'there is a reason for everything'. But are these the same?
Rousseau,Jean-Jacques: 'The Basic Political Writings', ed/tr. Cress,Donald A. [Hackett 1987], p.157