Chapter V.--On Laughter.
People who are imitators of ludicrous sensations, or rather of such as deserve derision, are to be driven from our polity. 
For since all forms of speech flow from mind and manners, ludicrous expressions could not be uttered, did they not proceed from ludicrous practices. For the saying, "It is not a good tree which produces corrupt fruit, nor a corrupt tree which produces good fruit,"  is to be applied in this case. For speech is the fruit of the mind. If, then, wags are to be ejected from our society, we ourselves must by no manner of means be allowed to stir up laughter. For it were absurd to be found imitators of things of which we are prohibited to be listeners; and still more absurd for a man to set about making himself a laughing-stock, that is, the butt of insult and derision. For if we could not endure to make a ridiculous figure, such as we see some do in processions, how could we with any propriety bear to have the inner man made a ridiculous figure of, and that to one's face? Wherefore we ought never of our own accord to assume a ludicrous character. And how, then, can we devote ourselves to being and appearing ridiculous in our conversation, thereby travestying speech, which is the most precious of all human endowments? It is therefore disgraceful to set one's self to do this; since the conversation of wags of this description is not fit for our ears, inasmuch as by the very expressions used it familiarizes us with shameful actions. 
Pleasantry is allowable, not waggery. Besides, even laughter must be kept in check; for when given vent to in the right manner it indicates orderliness, but when it issues differently it shows a want of restraint.
For, in a word, whatever things are natural to men we must not eradicate from them, but rather impose on them limits and suitable times. For man is not to laugh on all occasions because he is a laughing animal, any more than the horse neighs on all occasions because he is a neighing animal. But as rational beings, we are to regulate ourselves suitably, harmoniously relaxing the austerity and over-tension of our serious pursuits, not inharmoniously breaking them up altogether.
For the seemly relaxation of the countenance in a harmonious manner--as of a musical instrument--is called a smile. So also is laughter on the face of well-regulated men termed. But the discordant relaxation of countenance in the case of women is called a giggle, and is meretricious laughter; in the case of men, a guffaw, and is savage and insulting laughter. "A fool raises his voice in laughter,"  says the Scripture; but a clever man smiles almost imperceptibly. The clever man in this case he calls wise, inasmuch as he is differently affected from the fool. But, on the other hand, one needs not be gloomy, only grave. For I certainly prefer a man to smile who has a stern countenance than the reverse; for so his laughter will be less apt to become the object of ridicule.
Smiling even requires to be made the subject of discipline. If it is at what is disgraceful, we ought to blush rather than smile, lest we seem to take pleasure in it by sympathy; if at what is painful, it is fitting to look sad rather than to seem pleased. For to do the former is a sign of rational human thought; the other infers suspicion of cruelty.
We are not to laugh perpetually, for that is going beyond bounds; nor in the presence of elderly persons, or others worthy of respect, unless they indulge in pleasantry for our amusement. Nor are we to laugh before all and sundry, nor in every place, nor to every one, nor about everything. For to children and women especially laughter is the cause of slipping into scandal. And even to appear stern serves to keep those about us at their distance. For gravity can ward off the approaches of licentiousness by a mere look. All senseless people, to speak in a word, wine
"Commands both to laugh luxuriously and to dance,"
changing effeminate manners to softness. We must consider, too, how consequently freedom of speech leads impropriety on to filthy speaking.
"And he uttered a word which had been better unsaid." 
Especially, therefore, in liquor crafty men's characters are wont to be seen through, stripped as they are of their mask through the caitiff licence of intoxication, through which reason, weighed down in the soul itself by drunkenness, is lulled to sleep, and unruly passions are roused, which overmaster the feebleness of the mind.