A mountain that is sunken at the summit and does not jut out as a peak is able to form a lake and is stimulated by the moisture of the lake.  The image suggests that the mind be kept humble and free so that it can remain receptive to good advice.  A wise man draws people to himself by his own receptivity and is able to listen and instruct, thereby developing good relationships from which all may benefit. The universal mutual attraction between the sexes is represented here.  By keeping still within while experiencing joy without it is possible to prevent the joy from going to excess and hold it within proper bounds creating a sound foundation for successful personal and social relationships.