METONYMY, the most various of the rhetorical tropes,
is the substitution of one word for another when the ob-
jects are related as causes, effects, or adjuncts. Thus, in
the phrase, "To bring down one's gray hairs with sorrow to
the grave," the effect is put for the cause; gray hairs are
put for old age. We employ the same figure when we use
the author for his writings, the inventor for his invention,
&c. This trope was included by Aristotle under the general
term metaphor.