The importance of the black horse

From the text:

I couldn’t believe my eyes: horses going in a circle. I thought they were real. Then I saw they were not. They were made of wood, painted, going round and round to tootling music. I ran to them. I just stood there, overwhelmed. They were the most magnificent animals I had ever seen— red horses, blue horses, horses of all colors—draped in gold and flowers, heads high, hooves raised as
if prancing to the music.

It was the most beautiful of all the beautiful horses, and I had had my eye on it from the start. It was as black as the coal dust under my fingernails. It had gold tassels behind its ears and a flying tail and three golden hooves on the ground and one in the air. Its head was flung high and its mouth was open as if shouting to the horses of the world: Look at me!