"There is little need of commentary upon this clause. No man can well doubt the propriety of placing a president of the United States under the most solemn obligations to preserve, protect, and defend the constitution. It is a suitable pledge of his fidelity and responsibility to his country; and creates upon his conscience a deep sense of duty, by an appeal, at once in the presence of God and man, to the most sacred and solemn sanctions, which can operate upon the human mind." -- Joseph Story, Justice (1833)