Bhagavad Gita Verse 9, Chapter 15

shrotram chakshuhu sparshanam cha rasanam ghraanameva cha |
adhishthaaya manashchaayam vishayaanupasevate || 9 ||
 
The ear, eye and touch, taste and smell, taking support of these and the mind, it enjoys the sense objects.
 
shrotram : ear
chakshuhu : eye
sparshanam : touch
cha : and
rasanam : taste
ghraanam : smell
eva : only
cha : and
adhishthaaya : taking support
manaha : mind
cha : and
ayam : this
vishayaan : sense objects
upasevate : enjoys
 
Shri Krishna continues explaining how the jeeva, the individual soul, takes up a human body to carry out its transactions with Prakriti. We can use the wonderful Vedantic text "Drig Drishya Viveka", or "Discrimination of the seer and the seen", to examine this process in a little more detail. It explains, with almost mathematical precision, how the eternal essence begins to think of itself as a finite human entity. There are two main players in this process. One is the eternal essence, which is of the nature of infinite awareness and existence, explained in great detail in the second chapter. Let us call it "Om" here. The second player is avidya or ignorance, which exists in the realm of the illusory Maaya.
 
When Om and ignorance come into contact with each other, a fragment of Om is reflected in ignorance, just like a fragment of the sun as though appears in the water of a pot. As we saw earlier, this fragment is called the jeeva. Ignorance creates an apparent limitation, also known an upaadhi, which imposes a sense of incompleteness or finitude upon the jeeva. The jeeva seeks the help of the upaadhi to remove its sense of completeness. The upaadhi can exist in one of many modifications or states. Let us examine these modifications. The sense organs are modifications of this upaadhi that can contact different aspects of Prakriti. The mind is a modification of this upaadhi that can take input from the sense organs, compare that input with its memory, and present a complete picture of what was contacted. The ego is another modification that thinks of itself as the "I", just like a low level manager thinks of himself as the owner of the factory in the absence of the real owner.
 
Now let us examine the content of this shloka. After the end of its journey in one body, the jeeva travels with the mind and senses, the upaadhi in other words, in search of another physical body. When the ego aspect of the upaadhi associates itself with a tiny physical body inside a womb, based on the desires its wants to exhaust, it develops the notion "I am this body". It now begins to use the body to transact with the world. The human nose, for instance, is an inert object. But due to the association of the ego with the body, we think that the physical human nose is doing the smelling. The ego then uses the mind to generate the notion "I know that this smell is that of a rose". This finally leads the ego to generate the notion "This smell it pleasant, it makes me happy".
 
In this way, the jeeva gives up its power of reality, knowledge and happiness to the ego. The ego becomes the doer and the experiencer of the world. It has to constantly transact with the world in order to chase sense objects for happiness. It forgets the fact that it was happy to begin with. It gives reality to the domain of Prakriti, the three gunas, the visible and so called tangible world. But we should not forget that behind all this is the illusory mix up of Om and ignorance, the mix up of awareness and inertness. The Raamacharitamanas describes this mix up as "jada chetan ki granthi" or the knot between awareness and inertness.