Among the numerous elementary works which make the task of self-instruction pleasant and easy, none can excel, if any have equalled, the “Scientific Dialogues” of Joyce.  In these six little volumes, you will find a compendium of all preliminary knowledge; even these, however, easy as they are, require to be carefully studied.  The comparison of the text with the plates, the testing for yourself the truth of each experiment, (I do not mean that you should practically test it, except in a few easy cases, for your mind has not a sufficient taste for science to compensate for the trouble,) will furnish you with very important lessons in the art of fixing your attention.

“Conversations on Natural Philosophy,” in one volume, by a lady, is nearly as simple and clear as the “Scientific Dialogues;” it will serve usefully as a successor to them.  It is a great assistance to the memory to read a different work on the same subject while the first is still fresh in your mind.  The sameness of the facts gives the additional force of a double impression; and the variation in the mode of stating them, always more striking when the books are the respective works of a man and of a woman, adds the force of a trebled impression, stronger than the two others, because there is in it more of the exercise of the intellect, that is, on the supposition that, in accordance with the foregoing rules, you should think over each respective statement until you have reconciled them together by ascertaining the cause of the variation.

I shall now proceed to those lighter branches of literature which are equally necessary with the preceding, and which will supply you with the current coin of the day,—­very necessary for ordinary intercourse, though, in point of real value, far inferior to the bank-stock of philosophic and scientific knowledge which it is to be your chief object to acquire.  History is the branch of lighter literature to which your attention should be specially directed; it provides you with illustrations for all philosophy, with excitements to heroism and elevation of character, stronger perhaps than any mere theory can ever afford.  The simplest story, the most objective style of narrative, will be that best fitted to answer these purposes.  Your own philosophic deductions will be much more beneficial to your intellect than any one else’s, supposing always that you are willing to make, history a really intellectual study.

Tytler’s “Elements of History” is a most valuable book, and not an unnecessary word throughout the whole.  If you do not find getting by heart an insuperable difficulty, you will do well to commit every line to memory.  Half a page a day of the small edition would soon lay up for you such an extent of historic learning as would serve for a foundation to all future attainments in this branch of study.  Such outlines of history are a great assistance in forming the comprehensive views which are necessary on the subject of contemporaneous