Six in the second place means:
Lends grace to the beard on his chin.
The beard is not an independent thing; it moves only with the chin. The image therefore means that form is to be considered only as a result and attribute of content.
The beard is a superfluous ornament. To devote care to it for its own sake, without regard for the inner content of which it is an ornament, would bespeak a certain vanity.