The three addresses here presented treat of subjects which I myself did not choose, but which were suggested to me as likely to interest the persons before whom I was invited to speak. I have discussed these subjects from my own point of view; I have endeavoured — as indeed was demanded of me — to indicate tendencies, rather than to furnish detailed theories hence, in these three studies, devoid as they are of any external bond, the reader will quite easily discover a common groundwork, constituted by certain general ideas in the propagation of which I am anxious to share.