There are books said to be useless, and consequently harmless, but the conclusion, without being false, is not just; for we have just as much reason to believe they are dangerous as to admit the contrary. Now, if a book is indeed useless you cannot bear to read it, and since you do read it, it must certainly contain something interesting which renders it agreeable to you; it pleases some faculty of your soul, some habitual thought of your mind, some predominating disposition of your heart.
That a book may be read without profit is quite true. But that the same book can be read without danger of sustaining some loss is evidently false, unless that it be maintained that we are justified in having no proposed end for our actions; or that we may act solely for pastime which is diametrically opposed to the end for which we were created: Our time is too precious to be used indifferently. Again if there is in life anything that may be read or omitted without losing some advantage, or committing some evil, it is certainly not a book, for it always contains either some facts or some pictures, or some maxims capable of making an impression on your mind and heart.
The intelligence is formed and developed by means of language, and language, considered from this point of view, furnishes us with no idle words. Hence a useless book is, in the true acceptation of the term, a book that amuses the imagination and the heart. Now, whatever the soul receives through these channels must be of some importance for good or evil. Hence we are not justified, on the plea of indifference to accept any book that falls under our hands without being thoroughly examined and competently recommended.
Here, of course, a new difficulty occurs: at your age, and with your experience, you are unable to judge what books you should read; you are therefore obliged to follow the advice of others in the matter, but not the advice of all indiscriminately, as all are not competent to direct you in a matter of such grave importance. Popularity will give a wide circulation to a book bat can by no means recommend it; hence public opinion is not a rule that will guarantee you against deception.
Those in whom you place entire confidence to choose a book for you should themselves be recommended by their sincere and generous piety, the dignity of their life, the solidity of their judgment, strengthened by an extensive knowledge of men and things. Above all things be on your guard against the books recommended by worldly women, lovers of pleasure and parties; those whose light and frivolous minds sicken at serious thoughts, who are on their guard lest they may do too much for God, and who vainly endeavor to reconcile, in a monstrous union, the maxims of the world with those of the Gospel, the seductions of pleasure with the austerities of virtue, desiring to serve God and mammon.
If, by some negligence, or even in good faith; you open one of those books against which you have been warned, shut it the moment you feel your imagination excited by the images it offers, or when you perceive that the mind's curiosity becomes aroused to its agreeable narration of incidents, for it is almost always an unfavorable sign of a book that produces those and similar effects. Such is not the manner in which truth and virtue affect us. Their action is milder and calmer, and has the heart and will, rather than the imagination for its object. Hence, be on your guard, lest by some indiscretion you allow a poison to enter your soul, which is never more dangerous than when it seems least to be feared.
Finally, to resume in a few words, all that we have considered on the subject: If you would place the moral merit of a book beyond question, ask yourself if you would like to have its author for your spiritual director; do not think that this precaution is exaggerated or uncalled for; for between the author of a book and the reader there are relations established so intimate that they beget a kind of intellectual paternity, which produces deeper and more durable effects than you may be aware of.
To express the influence that our actions exercise over our life and over our fate, man is said to be the son of his works. For similar reason, it may be said of him, but more especially of woman, that he is the son of his readings, for reading forms such an important factor in the formation of the heart and mind that it often modifies our whole being. Besides, if you wish to profit by your reading, read only a few books, but read them well, with close attention, reflecting long and often on what you have read, identifying your very thoughts and sentiments with the subject matter of their pages. But let all this have its practical utility, let all those advantages find a living expression in your language, in your actions, and in your whole life.