We know too well from experience how often we fall, even when our intention is good... Our reason is exposed to so many forms of delusion, is liable to so many errors, stumbles on so many obstacles, is entangled by so many snares, that it is ever wandering from the right direction. Of how little value it is in the sight of God, in regard to all the parts of life, Paul shows, when he says, that we are not "sufficient of ourselves to think any thing as of ourselves," (2 Cor. 3: 5.) He is not speaking of the will or affection; he denies us the power of thinking aright how any thing can be duly performed. Is it, indeed, true, that all thought, intelligence, discernment, and industry, are so defective, that, in the sight of the Lord, we cannot think or aim at any thing that is right? To us, who can scarcely bear to part with acuteness of intellect, (in our estimation a most precious endowment,) it seems hard to admit this, whereas it is regarded as most just by the Holy Spirit, who "knoweth the thoughts of man, that they are vanity," (Ps. 94: 11,) and distinctly declares, that "every imagination of the thoughts of his heart was only evil continually," (Gen. 6: 5; 8: 21.) If every thing which our mind conceives, meditates plans, and resolves, is always evil, how can it ever think of doing what is pleasing to God, to whom righteousness and holiness alone are acceptable?

It is thus plain, that our mind, in what direction soever it turns, is miserably exposed to vanity. David was conscious of its weakness when he prayed, "Give me understanding, and I shall keep thy law," (Ps. 119: 34.) By desiring to obtain a new understanding, he intimates that his own was by no means sufficient. This he does not once only, but in one psalm repeats the same prayer almost ten times, the repetition intimating how strong the necessity which urged him to pray. What he thus asked for himself alone, Paul prays for the churches in general. "For this cause," says he, "we also, since the day we heard it, do not cease to pray for you, and to desire that ye might be filled with the knowledge of his will, in all wisdom and spiritual understanding; that you might walk worthy of the Lord," &c., (Col. 1: 9, 10.) Whenever he represents this as a blessing from God, we should remember that he at the same time testifies that it is not in the power of man.

~ John Calvin Institutes