B.K.S. Iyengar's book The Tree of Yoga is a lovely account of the practical and philosophical meaning of yoga. I believe a book has met its raison d'etre when it gets you to think about and reflect on your own life, and this book is likely to get you philosophizing about what yoga is about.
I believe everything is energy, everything that happens within our bodies, our thoughts, our emotions; it all has a vibrancy. As does the Earth and the Universe. It's all interconnected and emitting it's vibrancy at all times. Yoga is a means to become aware of the vibrancy in your body, in your thoughts and emotions. As B.K.S. Iyengar says “yoga is more than physical. It is cellular, mental, intellectual and spiritual- it involves man in his entire being.”
Iyengar beautifully says: “the science of yoga helps us to keep the body as a temple so that it becomes as clean as the soul. The body is lazy, the mind is vibrant and the soul is luminous. Yogic practices develop the body to the level of the vibrant mind so that the body and the mind, having both become vibrant, are drawn towards the light of the soul” .
Most of us give very little attention to what happens within our bodies throughout the day. Mostly, we're too busy thinking of our to do lists, our worries and obligations, and other things that keep us disctracted. We forget to really feel what our bodies, our intuition tells us. Only when pain comes along, do we become aware of our body's presence. And even that pain we try to ignore. But to really know yourself, to know your feelings, you must know your body. You must understand its signals and its intuitive signs. Only in truly knowing your body's communication, can we know how to heal ourselves. Energy is stored in each cell of our body; memories, emotions and divine secrets we have forgotten, are stored within our body, waiting to be released. As we see in nature, everything must be in movement, in flowing energy. Even a tree, static and immobile, is always changing and growing. Animals experience their emotions by acting them out instantly as they feel them, so they don't get stored within their bodies. This is how it should be with humans as well. Except, we evolved to be more restrained and reserved and we choose to hide and tone the emotions in, and they build up in our cells and create blockages. Yoga is an effective means of releasing energy that is built up within us.
Iyengar says: “You know how electricity is produced: water flows like a waterfall unto turbines which rotate under the action of the water to generate the current. So also, when we are performing asanas, we make the blood fall on every one of our cells like water onto a turbine, to release the hidden energy of our body and bring new light to the cells.” So yoga is a means to bring energy, life, to our cells, where our past experiences in form of emotion and memory are hidden. The energy is used to release that accumulated pressure and through movement, grant space, freedom and healing.
According to Iyengar “the effect of the asanas is to keep the skin, cells, nerves, arteries and veins, respiratory and circulatory systems, digestive and excretory systems, mind, intelligence, consciousness, all clean and clear.”
Knowing this, it becomes quite logical why you feel so good at the end of a yoga session. You didn't just move and breathe and stretch your body. You drenched your whole being with fresh, renewing energy.
Of course, to achieve this effect, yoga needs to be practiced more than sporadically. It needs to be practiced with discipline as often as possible, preferably as a daily habit.
Iyengar writes: “Each one has to train himself or herself, for without discipline we cannot become free, nor can there be freedom in the world without discipline. Discipline alone brings true freedom. If you have to gain health, do you think you can do so without discipline? Moderation in living is essential. This is why yoga starts with a code of conduct which each individual has to develop.”
The philosophy yoga is built on, is based on creating the best environment within yourself for yoga to have it's most powerful effect. Without the discipline of persistent practice, you won't gain the freedom that yoga offers your mind, body and soul.
Iyengar mentions 5 qualities, he refers to as yogic vitamins, which he thinks are required for an effective yoga practice: “This is how the asanas have to be performed. It cannot come in a day and it cannot come in years. It is a lifelong process, provided that the practitioner has the yogic vitamins of faith, memory, courage, absorption, and uninterrupted awareness of attention. These are the 5 vitamins required for the practice of yoga. With these 5 vitamins you can conquer the 5 sheaths of the body and become one with the Universal Self.”
These vitamins are what is needed to reach your full potential. This is how I interpret the use of these vitamins:
The faith in yourself and your own abilities and the faith in the power of the divinity of yoga which are found within the movements your body makes.
The memory of how your body is supposed to move and what it was built for by the creator, for it to reach it's full potential.
The courage to move in freedom and let yourself change to become who you are meant to be.
The absorption of the physical, emotional and spiritual effects that are taking place. The art of letting those effects flush over you and letting yourself become as one with them.
The uninterrupted awareness of attention to experience and skillfully guide and manipulate the changes within yourself that will make you the best version of yourself that you can be, not only for your own soul's healing, but for the healing of the soul of the world.