“For where there is much speech there is much vanity; how is this a benefit to man? For who knows what is good for man in life — numbering the days of his life is his vanity — they pass as a shadow. Who can declare to man what is coming after them under the sun?”
Verses 11 and 12 begin with the particle, כִּי (kiy), which joins the idea of these verses to verse 10. So, why is it vanity to make speech after speech? It is because the one with whom you are seeking to contend is God almighty who knows all things — even the inmost secrets of your heart. What good does it do to heap up words with such a God as this? Of what benefit is this vanity?
Why is it vain to do so? There are two reasons that Solomon sets before us. First, our days are fleeting — they are like a shadow in contrast to our eternal God. We might protest and say, “Look at this we have done or that we have established,” but what is that to God?
The second reason is that man (left unto himself) does not know what is good for him. Solomon’s life is a testimony to that as he sought time after time to find satisfaction in worldly things. No, God alone knows what is good for us. So, when the potter does something in our lives — or shapes us in a given way, our complaint and objection is vanity because what he is doing is what is best, right, and proper for our lives. And so, as chapter 6 is brought to a close, once again, Solomon is seeking to point us to the reality that if we are to find meaning, it will be found in submission to His will and His design for our lives.