It is not therefore surprising that a dogmatic composition or address, however solid, should not have any success either in conversation or in the pulpit, nor that a fine diction, whatever wit it may contain, should not bear fruit in a professor’s chair. It is not surprising that the fashionable world should not read writings that stand out in relief in the scientific world, and that the scholar and the man of science are ignorant of works belonging to the school of worldly people that are devoured greedily by all lovers of the beautiful. Each of these works may be entitled to admiration in the circle to which it belongs; and more than this, both, fundamentally, may be quite of equal value; but it would be requiring an impossibility to expect that the work which demands all the application of the thinker should at the same time offer an easy recreation to the man who is only a fine wit. For the same reason I consider that it is hurtful to choose for the instruction of youth books in which scientific matters are clothed in an attractive style. I do not speak here of those in which the substance is _sacrificed_ to the form, but of certain writings really excellent, which are sufficiently well digested to stand the strictest examination, but which do not offer their proofs by their very form. No doubt books of this kind attain their end, they are read; but this is always at the cost of a more important end, the end for which they ought to be read. In this sort of reading the understanding is never exercised save in as far as it agrees with the fancy; it does not learn to distinguish the form from the substance, nor to act alone as pure understanding. And yet the exercise of the pure understanding is in itself an essential and capital point in the instruction of youth; and very often the exercise itself of thought is much more important than the object on which it is exercised. If you wish for a matter to be done seriously, be very careful not to announce it as a diversion. It is preferable, on the contrary, to secure attention and effort by the very form that is employed, and to use a kind of violence to draw minds over from the passive to an active state. The professor ought never to hide from his pupil the exact regularity of the method; he ought rather to fix his attention on it, and if possible to make him desire this strictness. The student ought to learn to pursue an end, and in the interest of that end to put up with a difficult process. He ought early to aspire to that loftier satisfaction which is the reward of exertion. In a scientific lecture the senses are altogether set aside; in an æsthetic address it is wished to interest them. What is the result? A writing or conversation of the æsthetic class is devoured with interest; but questions are put as to its conclusions; the hearer is scarcely able to give an answer. And this is quite natural, as here the conceptions reach