And I gave my heart to know wisdom, and to know madness and folly: I perceived that this also is vexation of spirit.

And I turned myself to behold wisdom, and madness, and folly: for what can the man do that cometh after the king? even that which hath been already done.

I applied mine heart to know, and to search, and to seek out wisdom, and the reason of things, and to know the wickedness of folly, even of foolishness and madness:

This is an evil among all things that are done under the sun, that there is one event unto all: yea, also the heart of the sons of men is full of evil, and madness is in their heart while they live, and after that they go to the dead.

Ecclesiastes 1:17

Ecclesiastes 2:12

Ecclesiastes 7:25

Ecclesiastes 9:3

King James Bible