Nourishment of oneself, regarding the body, is represented in the lower trigram , while the upper trigram represents nourishment and care of others in a higher, spiritual sense.

If we wish to know someone, we need only observe on whom he bestows his care and what sides of his own nature he develops and nourishes.

Words are a movement going from within outward.  Eating and drinking are movements from without inward.  These movement can be modified by tranquillity, keeping the words coming out of the mouth from exceeding proper measure and keeping the food going into the mouth from exceeding its proper level.  In this way character is moulded.