Yogasanas are simple actions for keeping the internal and external parts of the body in good health. No activity can be performed wel I so long as the internal and external parts of  the body are not in good health. The body and the mind are closely interrelated. Both should be fully taken care of. Thousands of years ago, the people of ancient Greece believed in the principle'A sound mind in a sound body'. The whole system of their education was based on this principle. There are seven ways for the elimination of waste matter produced in the body by daily physical activities and functioning of the digestive system :(1) through left and right nostrils, (2) through left and right eyes, (3) through left and right ears, (4) through the mouth, (5) through the anus, (6) through the genitals and  (7) through the skin. Most diseases are the result of the absence of sufficient and regular elimination of waste matter such as urine and stool from the body. Yogic exercises help the process of elimination of waste matter from the body and keep the body in perfectly sound health.

Importance : The reasons why Yogasanas have a preference over other systems of physical exercises are enumerated below :
(  1  ) in other systems of physical exercise, the internal organs of the body do not get proper exercise, while Yogasanas give sufficient exercise to the internal organs of the body. Consequently, an individual can maintain good health and longevity of life.
(2) Only a small airy place and few equipments are required for practising Yogasanas.
(  3) Two or more individuals are required in other games, while Yoga is a solo-practice.
(4) Yogasanas have a greater impact on the mind and the senses than other physical exercises with the result that Yogasanas help to develop one's physical and mental powers to calm the mind and control the senses.
( 5) The practice of Yogasanas is not expensive as one practising Yogasanas needs no additional food.
( 6) There is sufficient elimination of stool and other
waste matter from the body through Yogasanas and hence the body has more resistance power to keep a disease away.

( 7) The body becomes flexible by Yogasanas. It be-comes active with an increased ability of doing any activity. One who performs Yogasanas looks younger in age and lives longer.
(8) The blood in the different blood vessels is purified through different Yogasanas.
( 9) The power of contraction and expansion of lungs is increased by practising Yogasanas and Pranayama. This results in the purification of blood to a great extent.
(10) Life span, youth and health depend upon the flexibility of the spinal cord. Yogasanas keep the spinal cord flexible.(1 1) Asanas require the least possible use of physical
energy. As a result, one feels less tired. This is the reason why Yogasanas are called a 'non-violent activity'.(12) One who practises Yogasanas becomes a morally good person.
(13) Yogasanas help the mind to experience tranquillity. There is progressive intellectual development because of the calm mind.
(14) Yogasanas stimulate different glands of the body. These stimulated glands produce secretions in proper proportion, which having mixed with blood helps the body to acquire a well-balanced growth.
(15) Diseases like constipation, gas-trouble, diabetes,blood pressure, hernia, headache, etc. can be cured by
practising Yogasanas and Pranayama.
(16) Yogasanas make possible not only physical and mental development but also intellectual and spiritual development.
(17) There is no restriction of age and sex for Yogasana aspirants. Our ancient sages had adopted this system for thousands of years with the result that they enjoyed sound health for a long time.

Hints : To take the full advantage of Yogasanas, it is advisable to follow the following points :
( 1) For practising Yogasanas, early morning is the ideal time. Before starting Yoga practices, the bowels and the bladder should be emptied. It is better to do Yogasanas after a bath because it makes the body light and active and one can practise Yogasanas with greater ease. If one wishes to take a bath again after practising Yogasanas, one should use warm water instead of cold water.
( 2) The ground for practising asanas should be level,clean and free from noise. Asanas should be practised on a mat or a carpet.
( 3) Clothing should be in accordance with the season.Mien should wear a loincloth or shorts. Women should wear a loose blouse and stretch pants.
(4) One should remain silent while practising asanas.While practising asanas, concentration should be on breath-ing and on the limbs which have a stress or strain. Concentration in the practice of Yogasanas is necessary for the all-round progress of the body and the mind.
( 5) Before one begins to practise other asanas, one should perform Shavasana in order to make breathing normal, the body and the mind tranquil.
( 6) Yogasana is a non-violent activity and therefore no force or jerk should be exerted in the practice of Yogasanas.
(7) There should be a gradual increase in the time duration in the practice of Yogasanas. By this process, the body becomes flexible and in a short time, it will easily accomplish a perfect state in each asana.
( 3) Yogasana is a scientific process which deals with tlue inlernal .Intl exlerndl parts of the body. A beginner should Mail practising Yogasanas after having learnt all their techniques under proper guidance.
( 9) The performer of asanas should take light food in order to keep the body light.
(10) If one is suffering from complicated diseases or severe fever, one should not practise asanas. Women should not practise asanas four months after conception, for three months after delivery and during menstruation. A woman-
aspirant should not as far as possible perform, without proper guidance asanas which involve lifting up the weight of the whole body on her hands.
(1 1) The number of asanas and the duration for each of them should be increased gradually. Practising many asanas on the first day should be avoided.
(12) Haste or quickness in coming to the final position from the initial position and vice versa should be avoided.
(13) After practising Yogasanas, Shavasana should be performed. Shavasana is a perfect asana. By Shavasana, the body gets speedy relaxation and becomes energetic.
(14) Yogasanas are supposed to be performed advanta-
geously in the right direction if the aspirant, after practising Yogasanas, feels no tiredness and has an increased capacity to work with his light and refreshed body.

Classification of Yogasanas : In order to understand Yogasanas and study them well, they have been classified as follows in this book :
( 1) Sitting Postures
( 2) Supine Postures
( 3) Abdominal Postures
(4) Hand-Postures
( 5) Knee-Postures (Kneeling Postures)
( 6) Leg-Postures (Standing Postures)
( 7) Head-Postures