The "taciturn force" is material progress, an inorganic dream-ideal
which Conrad very clearly delineates from the more primitive but more human ideal
of personal dictatorial rule. Charles Gould's silence stands in explicit opposition
to the pronunciamentos and eloquences of the dictators, because he is not
seeking personal rule, but rather the establishment of the rule of justice. However,
any successful dream-ideal implies rulership, and Gould has become the "King
of Sulaco" against his will, meaning that he must indulge in "words."
The desire not to rule -- to maintain silence -- is a constant stress within Charles
Gould's character and, by extension, within the inherent nature of material progress.