The stiff bristles are great for solid soaps and are especially ideal for whipping up a rich lather in a mug or shaving bowl. (businessinsider.com)
In the opening line of James Joyce's Ulysses, stately, plump Buck Mulligan bears «a bowl of lather on which a mirror and a razor lay crossed.» (firstthings.com)
In truth, even with those products designed to be used with a shaving brush, it's actually not necessary, but it will result in a better lather with less cream. (primandprep.com)