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 I am to constrain you by any law, it must be one by which I am also bound.

Man's duty is to improve himself; to cultivate his mind; and, when he finds himself going astray, to bring the moral law to bear upon himself.

To be beneficent when we can is a duty; and besides this, there are many minds so sympathetically constituted that, without any other motive of vanity or self-interest, they find a pleasure in spreading joy around them, and can take delight in the satisfaction of others so far as it is their own work. But I maintain that in such a case an action of this kind, however proper, however amiable it may be, has nevertheless no true moral worth, but is on a level with other inclinations. . . . For the maxim lacks the moral import, namely, that such actions be done from duty, not from inclination.

The wise man can change his mind; the stubborn one, never.

A lie is the abandonment and, as it were, the annihilation of the dignity by man.

All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.