Full Idea
The supreme principle of the doctrine of virtue is: Act in accordance with a maxim of ends that it can be a universal law for everyone to have.
Gist of Idea
The supreme principle of virtue is to find universal laws for ends
Source
Immanuel Kant (Metaphysics of Morals II:Doctrine of Virtue [1797], 395 Intro IX)
Book Reference
Kant,Immanuel: 'The Metaphysics of Morals', ed/tr. Gregor,Mary [CUP 1991], p.198
A Reaction
I'm not sure that any end can be a universal law. I certainly don't expect everyone to study philosophy. I suppose basic human ends, such as kindness and avoidance of suicide, are what he means. He's even more conformist than Aristotle!
Related Idea
Idea 21411 A duty of virtue is a duty which is also an end [Kant]