Annamaya Kosam
'Annam' means food and 'maya' means modifications. The body is the result of modification of food and hence called 'Annamaya'. The food eaten is digested. Its very essence becomes the source of new life. The child grows up and develops in strength and size due to the food eaten. Finally, we die to merge into food (Earth). The earth itself becomes the food we eat. So, we are born from food (earth) and go back to food (earth). When we identify with the Annamaya Kosa, we say-"I am tall, fair, healthy, beautiful, strong etc." Annamaya Kosam is our Gross Body (Sthula Sariram).

Pranamaya Kosam
The Vital Air Sheath pervades the Food Sheath. It is subtler than the food sheath. The five modifications of air, which control the main physiological functions of the body, are called 'Pranas'. They are: a) Prana b) Apana c) Vyana d) Udana and e) Samana. The five Pranas and the five organs of action together are called the 'Pranamaya Kosam'. Identified with it, a man says-" I am hungry, thirsty etc."

Manomaya Kosam
The Mind and the five sense organs of perception together form the mental sheath.
The mind is the seat of emotions like anger, love, jealousy, compassion etc. It is constituted of thoughts in a state of volition. It is the mind that perceives the objects of the world through the senses. If the mind does not back the sense organs, they cannot receive any stimuli. My eyes may be open; but I miss to see the object in front of me if my mind is elsewhere. It is only through the mind that the organs of action also respond to the world. Identified with the mental sheath, I say "I am happy, I am sad, I cannot hear etc.”

Vijnanamaya Kosam
The intellect and the five sense organs of perception together is the Intellectual Sheath. It is subtler than the former three sheaths. It controls and pervades them as well. The five senses are common to both the mental and intellectual sheaths, as perception involves both the mind and the intellect. 

Thoughts in a framework of decision-making are the intellect. Ignorance of the Self manifests first as the decision of the intellect as “I am the doer, I am finite etc.". This then gives rise to the notions - "I am tall, I am hungry, I am happy etc.”
Knowledge of the Self also takes place in the intellect as "I am infinite, I am pure happiness etc.” The intellect is the seat of the values of life. What we value, we try to emulate, run after or cherish. The intellect discriminates between right and wrong, real and unreal, good and bad etc. To innovate, create, discover, visualize, imagine, observe, conclude, inquire, question, recognize, assimilate etc. are intellectual abilities. The mind carries the sense perception to the intellect. Based on previous experience, it recognizes, understands and decides on the course of action. It conveys the same, through the mind, to the organs of action and the body to act accordingly. Hence, the intellect is called the 'Driver' of this vehicle of the body.
The Pranamaya Kosam, Manomaya Kosam and the Vijnanamaya Kosam together form our Subtle Body (Sukshma Sariram).

Anandamaya Kosam
The subtlest and the most pervasive of the five sheaths is the Bliss Sheath. It is otherwise called the Causal Body (Karana sariram). It is of the nature of ignorance of the world and the Self, yet endowed with the bliss of the Self.

When night falls, the world is covered by darkness. All objects and their distinctive characteristics merge into it. The objects are not destroyed. Only they are not perceived. As the day dawns, the distinctions manifest. Similarly, in deep sleep when only the causal body is at play, all dualities, the ego, anxiety, agitation, the world, the subtle and gross bodies etc. merge into total ignorance. Due to ignorance, it is said to be of impure nature.

The five sheaths form the covering, which conceals the jewel of the Self in its folds. They are modifications of the elements, born to die and are known to be different from ' I ' - the pure Self. The self is beyond all modifications, unborn, immortal and the witness of all. The Self is neither happy nor unhappy. It is always of the nature of pure bliss. We are thus different from the five sheaths.

Beyond the five Sheaths
The five sheaths are known by the Self as 'my body', 'my prana', 'my mind', 'my intellect', 'my bliss' and are, therefore, not the Self. The fact that 'I am not the five sheaths' is simple. But the most simple facts are the most difficult to grasp and accept. Our mind is so complicated and the habits of the past are so over-powering that one does not see the Truth. Even if the Truth is appreciated, it is not accepted. Even if it is accepted, it is not owned up to. Therefore, through continuous discrimination and firm resolve, one must uncover the Self and get liberated from the bondage of the five sheaths. Self, Consciousness, Creator, Atman, Brahman, Absolute, Purusha, Cosmic Person and Prajapati are some of the terms used to refer to this One Ultimate Reality, the Self.

MANTRA

1. ANNAMAYA KOSAM -FOOD SHEATH-PHYSICAL BODY

This section starts with the declaration of the goal that ‘the knower of Brahman reaches the Supreme’ (brahmavit apnoti param). Brahman is Truth, Knowledge and Infinity (satyam jnanam anantam brahma). It is in the space within the heart (nihitam guhayam). He who realizes the Self not only realizes the all-knowing Brahman but also attains everything he wants i.e. realizes the Bliss absolute, comes to experience all the joys of every living creature all at once.

The mantra gives a description of the evolution of the universe from fine to gross. It illustrates how the five great elements have emerged in a sequential order out of the Supreme, Brahman. Initially there is Brahman, Brahman everywhere. Brahman at this stage is nirguna, nirakara - without qualities and without a form. We cannot say what it is like.

•The first manifestation is space – akasa. Space is all pervasive and the subtlest; it has the quality sound.
•From space comes air – vayu, which has the qualities of sound and touch.
•From air comes fire – agni, which has the qualities of air and space apart from its own quality of form.
•From fire comes water – apah, which has its own quality of taste besides those of sound, touch and form.
•Then from water comes earth – prithvi, the grossest which has got its own quality of smell besides all the rest of the qualities mentioned above.

These great elements are described as the deities of the five sense organs as under : Akasa in the ears; air in the skin; fire in the eyes; water in the tongue and earth in the nose.

From this earth vegetation (aushadaya) grows and this vegetation produces food (anna). Then living beings (purusha) are manifested; food precedes living beings as the latter cannot survive without the former. The body is said to be annarasamaya, made of the essence of food. This food passes on from the parents to the child in a seed form (semen) and from that the body is made.

Then the Upanishad compares the human body to a bird. Our right and left arms are compared to wings. The lower part of our body is compared to tail which is called the support because without the tail a bird cannot fly. The whole body is balanced like a bird.

This is the description of annamaya kosa or the food sheath, the human body.

iti prathamo.anuvakah ..

End of Section 1 - Chapter 2