Ecclesiastes said that "all is vanity," Most modern preachers say the same, or show it By their examples of true Christianity: In short, all know, or very short may know it.
The need for sociability induce man to be in touch with his fellow men. However, this need might not ("ne saurait", Fr.) find its full (or complete) satisfaction in the conventional (or superficial, - "conventionnel", Fr.) and deceitful world, in which (or where) everyone is mainly (or mostly) trying to assert oneself in front of others ("devant les autres", Fr.), to appear, and hoping to find in society ("mondaine", Fr.) relationships some advantages for his interest and vanity (or vainglory or conceit", Fr).
Whether a man hides his bad qualities and vices or confesses them openly, his vanity wants to gain an advantage by it in both cases: just note how subtly he distinguishes between those he will hide his bad qualities from and those he will face honestly and candidly.
Some have lavish garments, carry sharp swords, and feast on food and drink. They possess more than they can spend. This is called the vanity of robbers. It is certainly not the Way.