It is very important to remember that medieval society functioned under very clear and well-defined stratas that originated from the belief of where power came from and who was who as determined by the strong religious belief of the time. Religion, particularly Christianity, played a major role in how medieval Europe formed socially and how people interacted as well. As such, given the illustration provided, this is what can be said.
First, the reason for the clergy and the pope being at the top was that in medieval times it was believed that God, and therefore his representatives, were at the head of society. They were in charge of blessing rulers selected by God. It was from divine power that all human power and social structures derived. The king, being the God-appointed earhtly power, was the heart of the social structure and from him all other levels derived. On one side, the king has the lords, men given the right by birth, not merit, to support the king and surround him, while the knights were men whose military prowes endowed them to protect the king and the land. While a noble´s function was to council the king, the knights were entrusted with the king´s protection. Finally, the serfs, or servants, were all people of low-born origin, poor in nature and without any important or noble ancestry, over who the king ruled and who were the basis of all medieval societies. The reason for the colors is to ascertain that this social ranking was acceptable to all members of society, even the serfs and the reason for not looking directly at the king, his lords, or the knights, is because they were believed to be too lowborn and unworthy to look at the higher hierarchies.
