Character means that the person derives his rules of conduct from himself and from the dignity of humanity. Character is the common ruling principle in man in the use of his talents and attributes. Thus it is the nature of his will, and is good or bad. A man who acts without settled principles, with no uniformity, has no character. A man may have a good heart and yet no character, because he is dependent upon impulses and does not act according to maxims. Firmness and unity of principle are essential to character.

Part III : Selection on Education from Kant's other Writings, Ch. I Pedagogical Fragments, # 14 - The Educational Theory of Immanuel Kant (1904)