De civilitate morum puerilium libellus

What modesty should be like.

The natural and genuine sense of shame should tinge the cheeks, not paint or artificial color. Although even this sense of shame must be so tempered that it neither turns into wickedness nor brings on a dysopia an excessive, crippling bashfulness or stupor, which is, as the Proverb says, the fourth degree of insanity. For in some people, this emotion is implanted so powerfully that it renders them very similar to a madman. This evil is tempered if a boy becomes accustomed to living among his elders, and exercises himself by acting in comedies.

Puffing out the cheeks.

To puff out the cheeks is a sign of pride; to let them drop is a sign of a despondent mind: the one is the way of a braggart soldier from Terence’s Eunuchus Thraso, the other is of Judas the betrayer.

al. Cain.

How the mouth should be set.

The mouth should not be pressed tight, which is the act of someone afraid of breathing in another person's breath, nor should it gape open, which is the act of fools; rather, it should be closed with the lips lightly kissing one another. It is also less decorous to make a smacking sound original: "popysmum" by repeatedly extending the lips, although this must be pardoned for adult men of rank passing through a crowd: for to them everything is becoming, but we are shaping a boy.