Ecclesiastes 1:13-17

13And I gave my heart to seek and search out by wisdom concerning all things that are done under heaven: this grievous labour hath God given to the sons of man to be exercised with it.1 14I have seen all the works that are done under the sun; and, behold, all is vanity and vexation of spirit. 15That which is crooked cannot be made straight: and that which is lacking cannot be numbered.2 16I spoke to my own heart, saying, Lo, I have come to great estate, and have gained more wisdom than all they that have been before me in Jerusalem: and my heart had great experience of wisdom and knowledge.3 17And I gave my heart to know wisdom, and to know madness and folly: I perceived that this also is vexation of spirit.