The Google dictionary defines "vain" as
 "having or showing an excessively high opinion of one's appearance, abilities, or worth."
 "producing no result; useless".
It reminds me of 1 Corinthians 13,
"If I speak in the tongues of mortals and of angels, but do not have love, I am a noisy gong or a clanging cymbal..."
I've often found the image of a gong booming quite humorous but if I were to realise how many of such booming gongs serving earthly kings there are in my life, my reaction would probably be quite different.
By Anchored in Christ.