The light dove, cleaving the air in her free flight, and feeling its resistance, might imagine that its flight would be still easier in empty space.

Live your life as though your every act were to become a universal law.

Experience without theory is blind, but theory without experience is mere intellectual play.

[Aristotle formal logic thus far (1787)] has not been able to advance a single step, and hence is to all appearances closed and completed.

Manners or etiquette ('accessibility, affability, politeness, refinement, propriety, courtesy, and ingratiating and captivating behavior') call for no large measure of moral determination and cannot, therefore, be reckoned as virtues. Even though manners are no virtues, they are a means of developing virtue.... The more we refine the crude elements in our nature, the more we improve our humanity and the more capable it grows of feeling the driving force of virtuous principles.

If justice perishes, human life on Earth has lost its meaning.

I am myself by inclination an investigator.