I think that when a person laughs, in the majority of cases he becomes repulsive to look at. Most often something banal is revealed in people's laughter, something as if humiliating for the laugher, though the laughing one almost always knows nothing of the impression he makes. Just as he doesn't know, as nobody generally knows, what kind of face he has when he's asleep. Some sleepers have intelligent faces even in sleep, while other faces, even intelligent ones, become very stupid in sleep and therefore ridiculous. I don't know what makes that happen; I only want to say that a laughing man, like a sleeping one, most often knows nothing about his face. A great many people don't know how to laugh at all. However, there's nothing to know here: it's a gift, and it can't be fabricated. It can only be fabricated by re-educating oneself, developing oneself for the better, and overcoming the bad instincts of one's character; then the laughter of such a person might quite possibly change for the better. A man can give himself away completely by his laughter, so that you suddenly learn all his innermost secrets. Even indisputably intelligent laughter is sometimes repulsive. Laughter calls first of all for sincerity but where is there any sincerity in people? Laughter calls for lack of spite, but people most often laugh spitefully. Sincere and unspiteful laughter is mirth, but where is there any mirth in our time, and do people know how to be mirthful? ... A man's mirth is a feature that gives away the whole man, from head to foot. Someone's character won't be cracked for a long time, then the man bursts out laughing somehow quite sincerely, and his whole character suddenly opens up as if on the flat of your hand. Only a man of the loftiest and happiest development knows how to be mirthful infectiously, that is, irresistibly and goodheartedly. I'm not speaking of his mental development, but of his character, of the whole man. And so, if you want to discern a man and know his soul, you must look, not at how he keeps silent, or how he speaks, or how he weeps, or even how he is stirred by the noblest ideas, but you had better look at him when he laughs. If a man has a good laugh, it means he's a good man. Note at the same time all the nuances: for instance, a man's laughter must in no case seem stupid to you, however merry and simplehearted it may be. The moment you notice the slightest trace of stupidity in someone's laughter, it undoubtedly means that the man is of limited intelligence, though he may do nothing but pour out ideas. Or if his laughter isn't stupid, but the man himself, when he laughs, for some reason suddenly seems ridiculous to you, even just slightlyknow, then, that the man has no real sense of dignity, not fully in any case. Or, finally, if his laughter is infectious, but for some reason still seems banal to you, know, then, that the man's nature is on the banal side as well, and all the noble and lofty that you noticed in him before is either deliberately affected or unconsciously borrowed, and later on the man is certain to change for the worse, to take up what's "useful" and throw his noble ideas away without regret, as the errors and infatuations of youth.
I am intentionally placing this long tirade about laughter here, even sacrificing the flow of the story, for I consider it one of the most serious conclusions of my life. And I especially recommend it to those would-be brides who are ready to marry their chosen man, but keep scrutinizing him with hesitation and mistrust, and can't make the final decision. And let them not laugh at the pathetic adolescent for poking his moral admonitions into the matter of marriage, of which he doesn't understand the first thing. But I understand only that laughter is the surest test of the soul. Look at a child: only children know how to laugh perfectlythat's what makes them seductive. A crying child is repulsive to me, but a laughing and merry child is a ray from paradise, a revelation from the future, when man will finally become as pure and simplehearted as a child.
Fyodor Dostoyevsky, The Adolescent (2003: 352-53)