There are four kinds of sheets of water:
(1) Flat (uttána) but deep in appearance (obhása);
(2) deep but flat in appearance;
(3) flat and flat in appearance;
(4) deep and deep in appearance.
So, also, there are four classes of people:
handsome in appearance but shallow in mind;
not handsome in appearance but deep in knowledge;
neither handsome nor wise;
both handsome and wise (A.ii.105-6).