This text is an excerpt from the book The Tree of Yoga, written by BKS Iyengar in 1968, following his previous works Light on Yoga, Light on Pranayama and the Art of Yoga. In the text, Iyengar makes the connection between the eight limbs of ashtanga yoga and the eight parts of a tree.
When you grow a plant you first dig the earth, remove the stones and weeds, and make the ground soft. Then you put the seed into the ground and surround it with the soft earth so carefully that when the seed opens it will not be damaged by the weight of the earth. Finally, you water the seed a little and wait for it to germinate and grow. After one or two days, the seed opens into a seedling and a stem grows from it. Then the stem splits into two branches and produces leaves. It steadily grows into a trunk and produces branches in various directions with many leaves.
Similarly, the tree of the self needs to be taken care of. The sages of old, who experienced the sight of the soul, discovered its seed in yoga. This seed has eight segments which as the tree grows give rise to the eight limbs of yoga.
The root of the tree is yama, which comprises the five principles of ahimsa (non-violence), satya (truthfulness), asteya (freedom from avarice), brahmacharya (control of sensual pleasure), and aparigraha (freedom from covetousness and possession beyond one’s needs). The observance of yama disciplines the five organs of action which are the arms, the legs, the mouth, the organs of generation and the organs of excretion. Naturally, the organs of action control the organs of perception and the mind – if one intends to do harm but the organs of action refuse to do it, the harm will not be done. The yogis therefore begin with control of the organs of action; yama is thus the root of the tree of yoga.
Then comes the trunk, which is compared to the principles of niyama. These are saucha (cleanliness), santosha (contentment), tapas (ardour), svadhyaya (self-study), and Isvara-pranidhana (self-surrender). These five principles of niyama control the organs of perception; the eyes, the ears, the nose, the tongue and the skin.
From the trunk of the tree several branches emerge. One grows very long, one grows sideways, one grows zigzag, one grows straight, and so on. These branches are asanas, the various postures which bring the physical and the physiological functions of the body into harmony with the psychological pattern of yogic discipline.
From the branches grow the leaves whose interaction with the air supplies energy to the whole tree. The leaves draw in the external air and connect it to the other parts of the tree. They correspond to pranayama, the science of breath, which connects the macrocosm with the microcosm and vice versa. Notice how, when inverted, our lungs give a representation of a tree. Through pranayama, the respiratory and circulatory systems are brought into a harmonious state.
The mastery of asanas and pranayama helps the practitioner to detach the mind from the contact of the body, and this leads automatically towards concentration and meditation. The branches of the tree are all covered with bark. Without the protection of the bark, the tree would be eaten away by worms. That covering protects the energy flowing inside the tree between the leaves and the root. The bark thus corresponds to samadhi, which is the inward journey of the senses from the skin towards the core of the being.
The sap of the tree, the juice which carries the energy on this inward journey, is dharana. Dharana is concentration – focusing the attention on the core of the being.
The tree’s fluid or sap links the very tip of the leaf to the tip of the root. The experience of this unity of the being from the periphery to the core, where the observer and the observed are one, is attained in meditation. When the tree is healthy and the supply of energy is wonderful, then the flowers blossom out of it. Thus, dhyana, meditation, is the flower of the fruit of the tree of yoga.
Finally, when the flower is transformed into a fruit, this is known as samadhi. As the essence of the tree is in the fruit, so the essence of the practice of yoga is in the freedom, poise, peace and beatitude of samadhi, where the body, the mind and the soul are united and merge with the Universal Spirit.