"A gentle hand may lead an elephant with a single hair."- Persian proverb
When we're riled up about something, we're blazing with the personal power we need to be effective and persuasive. When we raise our voices in agitation, however, we dissipate that energy. This is why most people yell in the first place: They have so much intense energy boiling inside that they're uncomfortable, and need to "blow off steam." Instead of wasting the force of our indignation, if we "keep a lid on" our anger, we can consciously harness it. There is tremendous power and wisdom in speaking quietly -- especially when we're raging inside.