Most single topics admit or require a considerable variety of books, each different from the other, and each supplementing the other.  Hence it is one of the best of practices in prosecuting a course of reading, to read every author who can cast any light upon the subject which we have in hand.  For example, if we are reading the history of the Great Rebellion in England, we should read, if we can, not a single author only, as Clarendon, but a half dozen or a half score, each of whom writes from his own point of view, supplies what another omits, or corrects what he under-or overstates.

But, besides the formal histories of the period, there are the various novels, the scenes and characters of which are placed in those times, such as Scott’s Woodstock; there are also diaries, such as those by Evelyn, Pepys, and Burton; and there are memoirs, such as those of Col.  Hutchinson; while the last two have been imitated in scores of fictions.  There are poems, such as those of Andrew Marvell, Milton, and Dryden.  There are also shoals of political tracts and pamphlets, of handbills and caricatures.

We name these various descriptions of works and classes of reading, not because we suppose all of them are accessible to those readers who live at a distance from large public libraries, or because we would advise everyone who may have access to such libraries, to read all these books and classes of books as a matter of course, but because we would illustrate how great is the variety of books and reading matter that are grouped around a single topic, and are embraced within a single period.

Every person must judge for himself how long a time he can bestow upon any single subject, or how many and various are the books in respect to it which it is wise to read; but of this everyone may be assured, that it is far easier, far more agreeable, and far more economical of time and energy, to concentrate the attention upon a single subject at a time than to extend it to half a score, and that six books read in succession or together upon a single topic, are far more interesting and profitable than twice as many which treat of topics remotely related.  A lady well known to the writer, of the least possible scholarly pretensions or literary notoriety, spent fifteen months of leisure, snatched by fragments from onerous family cares and brilliant social engagements, in reading the history of Greece as written by a great variety of authors and as illustrated by many accessories of literature and art.

Nor should it be argued that such rules as these, or the habits which they enjoin, are suitable for scholars only, or for people who have much leisure for reading.  It should rather be urged that those who can read the fewest books and who have at command the scantiest time, should aim to read with the greatest concentration and method; should occupy all of their divided energy with single centers of interest, and husband the few hours which they can command, in reading whatever converges to a definite, because to a single, impression.