A tree is a physical illustration of the spiritual life. It has a unique quality. It begins from a small seed, and then it grows and grows, until it becomes a full-fledged tree. How does this miracle take place? It is due to an inner quality of the tree. It is able to take food from everything: from soil, water, air, and sunlight. A seed is small, less than half-an-inch perhaps, but when it grows, it becomes a large tree, sometimes a few hundred feet tall. Man, also, is initially a seed. He is born with great potential. When he grows up, he can become like a giant; a superman. When he is born, he is like a seed. He possesses all the great human qualities. But all these things are in terms of potentiality, not in terms of actuality. It is for Man himself to turn this potentiality into actuality.
From The Spiritual Tree