A thing once done assumes a magical simplicity.  No matter what may have been the previous difficulty, or how much work may be involved in the result, yet, when the work is done, the problem solved, all the difficulty and labor promptly disappear from view, as if in dread of being led captive in triumphal procession after the Caesar who has mastered them.  Thus, it does not seem at all strange that we should have a book professing to guide us through all the intricacies of general literature; indeed, now that the work is put into our hands, it seems so easy of accomplishment that the only marvel would appear to be that we have had none hitherto.  Yet the conditions necessary to such a work are of the rarest to be found; not so rare, indeed, when each is considered separately, but rarely to be met with in combination.

In order even to attempt a work of this nature, its utility must first be fully appreciated; but, unfortunately, those whose need is the greatest, as being immediately present, would on that very account be incompetent to supply the need, while those who by dint of patient study have brought themselves up to the point of competency for the task no longer realize the want,—­just as men who have become rich by industry forget the necessities of poverty, which were the earliest spurs upon their energy.

The great majority of readers, therefore, have good reason to thank Mrs. Botta, that, after having met a great educational need in her own experience, she has benevolently set about supplying the same need in the experience of others.  The same motive which has led her to do this has also made her work, from the peculiar manner in which it is conducted, an important contribution toward a more perfect educational system than generally prevails; though we would not do her the injustice to imply that what she has done claims merit on this account alone or chiefly.  It does claim merit in this way, and of a very high order, because it avoids a prominent fault that vitiates most works intended to promote the general diffusion of knowledge.  The fault referred to is the same which De Quincey, in a note to his “Political Economy,” has called the greatest vice of teaching,—­namely, that the teacher does not readily enter into, as an inheritance, the difficulties of the pupil.  Merely to have corrected this fault, to have met the popular mind half-way and upon its own ground, was to furnish an important condition hitherto lacking in the field chosen.

The extent of the work—­embracing, as it does, the whole field of literature—­imposes other and more difficult conditions.  Originality, in any primary sense, was of course an impossibility; a single lifetime would not suffice even for the most cursory examination of original materials on so grand a scale.  It was necessary, therefore, to select and make use of the best authorities, critical and historical, those whose researches have been most valuable and comprehensive, in each particular department