Ecclesiastes 11:5
As you don't know what is the way of the wind, nor how the bones grow in the womb of her who is with child; even so you don't know the work of God who does all.
WEB
As thou knowest not what is the way of the spirit, nor how the bones do grow in the womb of her that is with child: even so thou knowest not the works of God who maketh all.
KJV
What Ecclesiastes 11:5 means
In Ecclesiastes, a clear-eyed sage stacks up things we cannot explain, the path of the wind and the forming of a child in the womb, to land one point: we do not grasp how God works, and we are meant to live and labor anyway.
Ecclesiastes 11:5 comes near the end of one of the Bible's strangest, most honest books. Its narrator, called Qoheleth (the Teacher), spends the book staring hard at life and admitting how much of it slips through the fingers. By chapter 11 he has turned practical. He tells the reader to cast bread on the water and to sow seed in the morning without holding back in the evening, because you cannot know in advance which effort will pay off. Verse 5 sits inside that counsel.
The setting is wisdom literature, written in a late, distinctive Hebrew for people who already knew that being devout does not buy you certainty. Qoheleth is not a cynic and not a cheerleader. He is a realist who keeps saying that the big picture is beyond us. Here he reaches for two everyday mysteries, the path the wind takes and the way a baby's bones form unseen in the womb, and uses them to make a larger claim: if you cannot explain these, you will not be able to trace out the work of the God who makes everything.
A detail lives in the Hebrew that most readers miss. The word for "wind" is ruach, which also means "breath" and "spirit." So the line can be read two ways, and translations split: some keep two separate images, the wind outside and the bones within, while others fold them into one, the mystery of how the breath of life enters a body in the womb. Either way the point holds. Qoheleth is naming the edge of human understanding, and standing at it without panic.