After Solomon advises us not to be overly righteous he reminds us of our fallen nature. Ecclesiastes 7:20 says, “Surely there is not a righteous man on earth who does good and never sins.” This biblical reality is repeated very 
often in scripture in both Testaments. One commentator says It “is an affirmation of the falleness of all humanity (cf. 1 Kgs. 8:46; 2 Chr. 6:36; Job 15:14–16; 25:4; Ps. 130:3–4; 143:2; Prov. 20:9; Rom. 3:9–18, 23; 1 John 1:8–2:1). This shows the foolishness of perfectionism and/or human effort (cf. vv. 16–18).”
Keeping the context of the passage, the verse immediately preceding this verse expounds on the value of true wisdom. Verse 19 says, “Wisdom gives strength to the wise man more than ten rulers who are in a city.” He then proceeds to give us the most profound piece of wisdom that he has. When the scriptures teach us that “the fear of the Lord is the beginning of wisdom” it necessitates our taking our rightful place amongst the whole population of the human race; we are all sinners. It is in the reality of our weakness that true strength can be found. This may have been the basis for Paul’s comment that it was in his weakness that he became strong. I would argue further that it’s the reality of our sinfulness that becomes the very foundation for living a life of integrity. When we fail to come to grips with our own sinfulness, we inevitably “must redefine sin or diminish the standard of holiness.” It takes the focus off of God and puts it on myself. It can lead to devastating result. Church history is full of examples. Let me give you one of the more extreme examples to make my point. I had to write a paper in college on the Oneida community.
It was founded by John Humphrey Noyes and was based on a notion of perfectionism. The Oneida Community was the best known of about fifty utopian communes that operated in New York State in the second half of the nineteenth century. Oneida members (about three hundred of them) started a tableware company that still thrives today. It was hailed in its day as a model of Christian brotherhood and holiness. It was discovered in 1879 that the Oneida Community also practiced communal marriage. Every woman was considered married to every man, and all were at liberty to have sex with anyone else in the community they chose. Worse, children were expected to be sexually active as soon as they were old enough. Noyes himself usually initiated the young girls as soon as they reached puberty. Noyes, like all too many perfectionists, simply adapted moral standards to suit his own preferences. I know this is an extreme example, but as one writer said, “Ultimately all perfectionists are forced to devise down-scaled definitions of sin, holiness, and perfection that can accommodate the imperfections of human carnality.” A life of integrity begins with the wisdom that we are all sinners. Admitting it is a huge step towards a healthy, happy and wholesome life. On husband said, “Now, my wife’s parents have not spoken to me in four years, ever since I made a sarcastic remark about their perfectionist tendencies at a Thanksgiving dinner—ironically, they had forgotten to bring the apple pie.”