This is an extended critical book-report on Sir John Herschel's Preliminary Discourse on the Study of Natural Philosophy (1831).¹ The book is not such a masterpiece as to deserve detailed study, but it contains one important discovery and a few interesting passages which I shall comment on. It expounds a popular philosophy of success which will become amply clear from the present summary of its presentation and ideas and which will be discussed in the concluding section. It expresses the atmosphere of the time in which it was written, as I shall endeavor to illustrate chiefly in my introductory and concluding sections. It influenced the literature considerably, if for no other reason than that the writings of both William Whewell and John Stuart Mill follow in its wake. Its very conception as an updated version of Bacon's Novum Organum is a forerunner to Whewell's Novum Organum Renovatum. But I shall not discuss Herschel's influence on posterity here, since this is a topic for a separate essay.