Body being the grossest of the five sheaths, other four sheaths influence it much more than body influencing the others. Note that this is very different from Buddhist approach... where Body is the interface between the world, others and the self. It is like the screen on which the movie projects and has as much control on the subtler elements as the screen has on the movie. But beware — without a screen, there is no movie!

Prana or vital body is what makes the body come alive (literally). As long as the energy or life force is moving through the body, various bacterial and viral organisms do not take over and the moment the vital force is gone, they destroy the body. There are five distinct ways in which vital force or prana controls the body (including throwing up, flatulence, imbalance and balance in the stomach, breath etc). Another important aspect of prana is that it controls our emotions. By breathing differently, we can change our emotions consciously. For example, when a deep emotion grips us, we stop breathing or we hyperventilate. When we are sobbing or experiencing sadness, by changing our breath pattern, we can gain control over our emotions. Try it yourself and you can also ask others when they are in your presence experiencing rage, sadness, anger or grief. When they do listen to you and alter their breathing pattern, they begin to shift their state.

Manas or lower mind is like a taxi dispatcher of a cab company. Mind attempts to make sense of the input from all the five senses and directs our attention, action (motor functions) and either creates confusion or solidifies intention. So desires, association and clarity are operated at this level and manifested at prana and the body level. When the mind is clear, we begin to gain certain equanimity and when it is confused, we get overwhelmed by the sensory inputs. Just like the dispatcher in a taxi company can put various customers, drivers together and give directions to various taxi drivers to go to different locations optimizing business, the manas controls both perceptions and actions of our senses. In terms of happiness, the mind is a powerful visualizer and tranquilizer. So at manas level we create addictions, attachments and aversions.

Buddhi or the higher mind is subtler than the manas. Buddhi is the owner of the taxi company while the manas is the dispatcher. It sets directions, gives guidelines for the dispatcher to work with. Buddhi gives us the ability to discern, discriminate and make effective decisions and you can call it intelligence. Once the decisions are made at this level, manas takes over the execution through prana and the body. If we are not clear at this level, if we don’t think systemically and have no vision, then we end up focusing just on the short term and lose out the future. In other words - strategy, direction, purpose and vision are connected to our higher mind. When we do these exercises just for making our colleagues happy and not engage our higher mind, passion is never evoked and commitment to action is out of question. We might have an intention to follow through (manas level) but behavior will not change unless buddhi is engaged. This level is what differentiates one person from the other. Happiness can be a choice that one makes at this level and that percolates into how our manas seeks goals that are connected with happiness. If we decide at this level that we are not happy, then lower mind helps us find the evidence that we are looking for. Buddhi gives us the ability to discriminate ourselves and our intelligence differentiates others from us and the identity is formed at this level. When I compare myself with others, I feel happy or unhappy and the cycle continues.

Ananda or bliss body is the subtlest of all the five sheaths. It is the subtle ego in us. While intelligence or buddhi helps us to discriminate, we don’t have to follow that direction. We do listen to our intelligence when we are unhappy with who we think we are and are content when we are happy with ourselves. Discrimination is wonderful in dealing with others and the world whereas happiness is what shapes our experiences and ultimately our 'I-sense'. In other words, happiness creates freedom or bondage of the human spirit. When we are free, we experience the oneness, "the flow" (a la Mihaly Csikszentmihalyi ) and the interconnectedness with the universe. In that respect, according to Vedanta, happiness is the root cause of the universe. Through happiness the universe is created, sustained and dissolved because subtly that is what allows us to take action by subverting our intelligence and manas to go in the direction of pursuit of happiness.

In another part of the same Upanishad, we find a scale of happiness. The ideal person is defined as young, strong and virile and that person’s happiness is the basic unit of happiness. From there, we discuss celestial beings, gods, kings of gods, teachers of gods all the way to Brahman. According to that scale, the ananda of Brahman or a person who has discovered his/her true self to be none other than Brahman is 10 followed by 19 zeros of units. That is 100 times the billion times the billion times of the ideal person’s happiness.