A human being can be compared to a tree.
The roots correspond to the stomach and sexual organs, for human beings are rooted in the earth by means of their stomach, which enables them to nourish themselves, and by their sexual organs, which enable them to reproduce.
The trunk is represented by the lungs and the heart, that is to say, the respiratory system and the arterial and venous system through which the blood circulates.
The elaborated sap flows down to nourish the tree, while the upward flow carries the raw sap to the leaves where it is transformed.
The same principle is at work in our bloodstream, whereby the arteries carry the clean, pure blood, and the veins carry the tainted blood.
The leaves, flowers and fruit of a tree correspond to the head. All our thoughts represent our fruit because it is through the mind that a human being bears fruit.