I have received important assistance in composing this book from my pupil, Mr. Henry E. Bourne, who was graduated at the Yale Divinity School the present year. On the basis of manuscript notes of my lectures, at my request, and under my supervision, he undertook to write out a number of chapters, to be afterwards submitted to me for amendment. He more than fulfilled his task, as well in regard to the contents as the form of these chapters; for he incorporated matter of much value, derived from his own reading. I owe, moreover, to the diligence of this promising young scholar the making of the Index.