The poor man sweeps his floor until it is spotless. The poor woman combs her hair until it is neat and tidy. Neither produces a wonderful sight, but these actions bespeak a sensibility of elegance.
An unruly horse can still be ridden after taming. Melted metals from the smelting furnace are returned to the mould.
To constantly hear words that grate upon the ear and to always encounter matters that unsettle the heart—this is the whetstone for cultivating virtue.