Because the feathers do not grow from the rump, but all up the back. A range of short, brown, stiff feathers, about six inches long, fixed in the rump, is the real tail, and props up the long feathers, or train, which is top-heavy when set on end. By a strong muscular vibration, these birds can make the shafts of their long feathers clatter like the shafts of a sword-dancer. - G, White.
Because they were said to be the nutriment of lovers, and the viand of worthies. - Mills.
Because knights associated them with all their ideas of fame, and vowed by the peacock, as well as by the ladies, to perform their highest enterprises. - Mills.