In its main features the Declaration of Independence is a great spiritual document. It is a declaration not of material but of spiritual conceptions. Equality, liberty, popular sovereignty, the rights of man — these are not elements which we can see and touch. They are ideals. They have their source and their roots in the religious convictions. They belong to the unseen world. Unless the faith of the American people in these religious convictions is to endure, the principles of our Declaration will perish. We can not continue to enjoy the result if we neglect and abandon the cause.

Speech on the Anniversary of the Declaration of Independence (1926)