Full Idea
The moral law is holy (unyielding), although all the moral perfection to which man can attain is still only virtue, that is, a rightful disposition arising from respect for the law.
Gist of Idea
Moral law is holy, and the best we can do is achieve virtue through respect for the law
Source
Immanuel Kant (Critique of Practical Reason [1788], I.II.II.V)
Book Reference
Kant,Immanuel: 'Critique of Practical Reason (Third edition)', ed/tr. Beck,Lewis White [Library of Liberal Arts 1993], p.135
A Reaction
In comparison with Aristotle's view of virtue this is very passive and external. Aristotle doesn't need laws for virtue, he needs inner harmony and a grasp of what has high value.