And, as a general rule, it is more advisable to show your intelligence by saying nothing than by speaking out; for silence is a matter of prudence, whilst speech has something in it of vanity. The opportunities for displaying the one or the other quality occur equally often; but the fleeting satisfaction afforded by speech is often preferred to the permanent advantage secured by silence. The feeling of relief which lively people experience in speaking aloud when no one is listening, should not be indulged, lest it grow into a habit; for in this way thought establishes such very friendly terms with speech, that conversation is apt to become a process of thinking aloud. Prudence exacts that a wide gulf should be fixed between what we think and what we say. At times we fancy that people are utterly unable to believe in the truth of some statement affecting us personally, whereas it never occurs to them to doubt it; but if we give them the slightest opportunity of doubting it, they find it absolutely impossible to believe it any more. We often betray ourselves into revealing something, simply because we suppose that people cannot help noticing it,--just as a man will throw himself down from a great height because he loses his head, in other words, because he fancies that he cannot retain a firm footing any longer; the torment of his position is so great, that he thinks it better to put an end to it at once. This is the kind of insanity which is called _acrophobia_. But it should not be forgotten how clever people are in regard to affairs which do not concern them, even though they show no particularly sign of acuteness in other matters. This is a kind of algebra in which people are very proficient: give them a single fact to go upon, and they will solve the most complicated problems. So, if you wish to relate some event that happened long ago, without mentioning any names, or otherwise indicating the persons to whom you refer, you should be very careful not to introduce into your narrative anything that might point, however distantly, to some definite fact, whether it is a particular locality, or a date, or the name of some one who was only to a small extent implicated, or anything else that was even remotely connected with the event; for that at once gives people something positive to go upon, and by the aid of their talent for this sort of algebra, they will discover all the rest. Their curiosity in these matters becomes a kind of enthusiasm: their will spurs on their intellect, and drives it forward to the attainment of the most remote results. For however unsusceptible and different people may be to general and universal truths, they are very ardent in the matter of particular details.