In Ma's poems, gold is the tail of the brain. What does it mean? What does it symbolize?

Golden gongs, brocade and golden whip are precious saddles, which symbolize the importance of horses.

A gold bridle is worn on the horse's head.

Also refers to the faucet made of gold. The poem "History of Horse" expresses the feelings and resentment of talented people who are different, ambitious and untimely by chanting, praising and lamenting the fate of horse. Its expression method belongs to figurative style, but this poem is unique in the use of figurative techniques.