"Before you start any Qigong training you must first understand the three treasures: Jing (Essence), Qi (Internal Energy), and Shen (Spirit). They are also called the three origins or the three roots, because they are considered the origins and roots of your life. Jing means Essence, the most original and refined part. Jing is the original source and most basic part of every living thing, and determines its nature and characteristics. Qi is the internal energy of your body. It is like the electricity which passes through a machine to keep it running. Qi comes either from the conversion of the Jing which you have received from your parents, or from the food you eat and the air you breathe. Shen is the center of your mind and being. It is what makes you human, because animals do not have a Shen. The Shen in your body must be nourished by your Qi or energy. When your Qi is full, your Shen will be enlivened.
"Chinese meditators and Qigong practitioners believe that the body contains two general types of Qi. The first type is called “Pre-birth Qi”, and it comes from converted original Jing, which you get from your parents at conception. The second type, which is called “Post-birth Qi”, is drawn from the Jing of our food and air. When this Qi flows or is led to the brain, it can energize the Shen and soul. This energized and raised Shen is able to lead the Qi to the entire body.
"Your body requires many kinds of Jing. Except for the Jing, which you inherit from your parents, which is called Original Jing, all other Jings must be obtained from food and air. Among all of these Jings, Original Jing is the most important. It is the root and the seed of your life, and your basic strength. After birth this Original Jing stays in its residence- the kidneys, which are considered the root of your Jing. When you keep this root strong, you will have sufficient Original Jing to supply your body. Although you cannot increase the amount of original Jing you have, Qigong training can improve the quality of your Jing. Qigong can also teach you how to convert your Jing into Original Qi more efficiently, and how to use this Qi effectively.
"Qi is converted both from the Jing which you have inherited from your parents and from the Jing which you draw from your food and air. Qi that is converted from the Original Jing which you inherit is called Original Qi. Just as Original Jing is the most important type of Jing, Original Qi is the most important type of Qi. It is pure and of high quality, while the Qi from food and air may make your body too positive or too negative, depending on how and where you absorb it. When you retain and protect your Original Jing, you will be able to generate Original Qi in a pure, continuous stream. As a Qigong practitioner, you must know how to convert your Original Jing into Original Qi in a smooth, steady stream.
"Since your Original Qi comes from your Original Jing, they both have the kidneys for their root. When you kidneys are strong, the Original Jing is strong, and the Original Qi converted from this Original Jing will also be full and strong. This Qi resides in the Lower Dan Tian in your abdomen. Once you learn how to convert your original Jing, you will be able to supply your body will the Qi it needs.
"Shen is the force which keeps you alive. It has no substance, but it gives expression and appearance to your Jing. Shen is also the control tower for the Qi. When your Shen is strong, your Qi is strong and you can lead it efficiently. The root of Shen (Spirit) is your mind (Yi, or intention). When your brain is energized and stimulated, your mind will be more aware and you will be able to concentrate more intensely. Also, your Shen will be raised. With an abundant Qi supply, the mind can be energized, and can raise the Shen and enhance your vitality." *
* Dr. Yang, Jwing-Ming, The Essence of Taiji Qigong