I spent some time looking at the words in the original languages that are translated “vain.” In the Old Testament the word has the sense of aimlessness, useless activity. In the New Testament similarly the meaning is empty or ineffective. The email that included the reference to Proverbs 4:23, reminded me of the charge to be diligent, which charge Peter reminds of us multiple times; 2 Peter 1:5, 10, 15; 3:14.
How do we resolve all this? It seems to me that we have to be diligent to trust in the Lord alone in all that we do. Not in our gifts, not in our abilities, but in Him. As Paul said in 15:10, it is the grace of God that allowed him to work harder. Our capacity to serve is a product of our rest and trust in Him. It is stunningly counter intuitive.
To just work harder, to launch into the fray, is like shooting without aiming. Aimless, empty, useless pursuit. This idea shows up multiple times – can you think of other places or stories that reinforce or repeat this idea?