Translated from Italian by me (WTFPL).
Eleandro. Therefore those are greatly mistaken who say and proclaim that the perfection of man consists in the knowledge of truth, and that all his ills arise from false opinions and from ignorance, and that mankind will at last be happy when each man, or most men, shall know the truth, and according to that alone compose and govern their lives. And this is said by nearly all the philosophers, ancient and modern. Now according to your judgment, those truths which are the substance of all philosophy ought to be concealed from the majority of men; and I believe you would readily agree that they ought to be ignored or forgotten by everyone: for, once known and kept in the mind, they can do nothing but harm. Which is the same as saying that philosophy must be extirpated from the world. I am not unaware that the final conclusion to be drawn from true and perfect philosophy is that one must not philosophize. From this it follows, first, that philosophy is useless, because to this end of not philosophizing, it is not necessary to be a philosopher; secondly, it is most harmful, since that final conclusion cannot be learned except at one’s own cost, and once it is learned, it cannot be put into practice; it being not in man’s power to forget the truths once known, and it being easier to lay aside any other habit than that of philosophizing. In short, philosophy, hoping and promising at the outset to cure our ills, ends by vainly wishing to remedy itself.
Giacomo Leopardi – Small Moral Works – Dialogue between Timandro and Eleandro