Do what is right, though the world may perish.

This is quoted as Kant in Building Academic Language: Essential Practices for Content Classrooms, Grades 5-12 (2007) by Jeff Zwiers, p. 202, but apparently derives from Kant's arguments in support of the far older Latin proverb Fiat iustitia, pereat mundus — "Do what is right though the world should perish." which was the subject of an essay: "Kant on the Maxim 'Do What Is Right Though the World Should Perish'" by Sissela Bok, in Argumentation 2 (February 1988). There was also a similar latin proverb Fiat iustitia ruat caelum — Let justice be done though the heavens fall.