What can I know? What ought I to do? What can I hope?
Nothing is divine but what is agreeable to reason.
Morality is not the doctrine of how we may make ourselves happy, but how we may make ourselves worthy of happiness.
All the interests of my reason, speculative as well as practical, combine in the three following questions: 1. What can I know? 2. What ought I to do? 3. What may I hope?