One of the main topics of Proverbs is the foolish contrasted with the wise. While in English there is one word to describe a fool, in Proverbs, five separate Hebrew words are used, which describes a progression of foolishness from simple to depraved.
first: the simple fool
pey פ, ף = the mouth, thus open, blow, scatter, edge
tav ת = crossed sticks, thus mark, sign, signal, monument
hey ה = man with upraised arms, thus look, reveal, wonder, worship, breath
The primitive verbal root pey + tav is the Hebrew word for intercourse, as the woman’s “open mouth” receives the man’s “post”. The parable being told of foolishness, then, is to have an open mind (pey) which receives (tav) whatever comes before it as a revelation, or a wonder (hey); it is to be naive, gullible.
It is wisdom to have a guarded mind. But simplicity is the natural state of all children by virtue of their age. It is a gift from God to parents, that children are born this way, because children naturally receive whatever their parents teach them, good or bad, learning by their example as well as by their words.
In the Hebraic way of doing things, a child at age 13 becomes a son (or daughter) of the commandment (bar or bat mitzvah); Yeshua, however, by the time He was 12, had wisdom which astounded the teachers in the Temple.
So we can see that one of the most important tasks God has entrusted to parents is to guide their children in helping them respond to the call of wisdom, rather than to the call of folly.
The proverbs of Solomon the son of David, king of Israel: To know wisdom and instruction, to perceive the words of understanding, to receive the instruction of wisdom, justice, judgment, and equity; to give prudence to the simple, H6612 to the young man knowledge and discretion. Pro 1:1-4
This is why the LORD commands parents:
“And these words which I command you today shall be in your heart. You shall teach them diligently to your children, and shall talk of them when you sit in your house, when you walk by the way, when you lie down, and when you rise up. You shall bind them as a sign on your hand, and they shall be as frontlets between your eyes. You shall write them on the doorposts of your house and on your gates. Deu 6:6-9
The simple are corrected by a combination of verbal instruction and corporal discipline for willful rebellion (not mere childishness). If a child has not been turned from foolishness by the time he is 12 or 13, he is in danger of becoming the next, more destructive fool that Proverbs describes.