What happens...when I make a commitment is that I enter a new form of relationship. The root meaning of "commitment" lies in the Latin mittere—"to send." I "send" my word into another. Ordinary dictionary uses for "commitment" include "to place" somewhere (as "to commit to the earth," or "to commit to prison," or "to commit to memory"); and "to give in charge," "to entrust," "to consign to a person's care" (as in "to commit all thy cares to God"). When I make a commitment to another person, I dwell in the other by means of my word.
from Personal Commitments: Beginning, Keeping, Changing (1986), p. 17.