It is because words cannot be clearly heard in battle, drums and gongs are used;
it is because troops cannot see each other clearly in battle, flags and pennants are used.
Therefore, in night battles use torches and drums;
in day battles use flags and pennants.
Drums, gongs, flags, and pennants are used to unite men's eyes and ears.
When the men are united, the brave cannot advance alone, the cowardly cannot retreat alone.
Sun Tzu.
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semantics is not always just pedantic quibbling. ~ douglas r. hofstadter