Please answer a question about the following article about Red:

Red played an important role in Chinese philosophy. It was believed that the world was composed of five elements: metal, wood, water, fire and earth, and that each had a color. Red was associated with fire. Each Emperor chose the color that his fortune-tellers believed would bring the most prosperity and good fortune to his reign. During the Zhou, Han, Jin, Song and Ming Dynasties, red considered a noble color, and it was featured in all court ceremonies, from coronations to sacrificial offerings, and weddings.

How many elements did the Chinese philosophers think the world was made of?
five