A disciple of Locke, and a man of considerable and various powers, the non-conformist divine Isaac Watts, produced perhaps the first considerable didactic treatise on Study. I refer, of course, to his well-known work entitled "The Improvement of the Mind"; on which, he tells us, he was occupied at intervals for twenty years. It has two Parts: one on the acquisition of knowledge; the other on Communication or leaching. The scheme is a very wide one. Observation, Reading, attending Lectures, Conversation,--are all included. To the word "Study," Watts attaches a special meaning, namely Meditation and Reflection, together with the control or regulation of all the exercises of the mind. I doubt if this meaning is well supported by usage. At all events it is not the signification that I propose to attach to the term. Observation is an art in itself: so is Conversation, whether amicable or contentious. The _proportions_ that these exercises should bear to reading, would fairly claim a place in the complete Art of Study. Watts has two short chapters on Books and Reading, containing sensible remarks. He urges the importance of thorough mastery of select authors; but assumes a power of discriminating good and bad beyond the reach of a learner, and does not show how it is to be attained. He is very much concerned all through as to the moral tone and religious orthodoxy of the books read, he also reproves hasty and ill-natured judgments upon the authors. Watts's Essay is so pithily written, and so full of sense and propriety, that it long maintained a high position in our literature; he tells us, that it had become a text-book in the University. I do not know of any better work on the same plan. A "Student's Guide," by an American named Todd, was in vogue with us, some time ago; but anyone looking at its contents, will not be sorry that it is now forgotten. It would not, however, be correct to say that the subject has died out. If there have not been many express didactic treatises of late, there has been an innumerable host of small dissertations, in the form of addresses, speeches, incidental discussions, leading articles, sermons--all intended to guide both young and old in the path of useful study. What to read, when to read, and how to read,--have been themes of many an essay, texts of many a discourse. According as Education at large has been more and more discussed, the particular province of self-education, as here marked out, has had an ample share of attention from more or less qualified advisers.