Bhava and rasa are of primary importance in this cycle. In this time and age, when the mother cares not for her child, when children care not for each other; bhava and rasa become even more pertinent to the cause towards life.
Rasa is extract, of and from life, seeping into each/every corner of your being, the rasa can be explained in a minute mundane sense like the effects of alcohol. Once in a while (well maybe more often than that), if only people asked themselves what they do in the entire span of day and night (sun to moon to sun) which brings them that rasa in their life, we would end up with a lot less conflicts and a lot more wisdom.
Rasa is taste, it is refined and at the same moment all encompassing, to find the rasa in one's life, one has to experience how much ever one can, the rasa develops automatically side by side. It is at first the by-product of the way you have lived your life to entirety, but it is something all together different. It could be said (words are misinterpreted- and if mine are; dont blame me) that rasa is the true base of life, and the way we develop it, is through struggle, experience and continuously renewing our bhava- towards the internal and external framework. (this is abstract, but what to do, so are we :!)
The real problem arises because we do not tend to search/seek this rasa in our life. It is difficult for some, while it overflows without any rhyme nor reason from others. It could be called un fair, that many seek their entire life to find their rasa; their true reason for breathing, while others know it from the instant they were hatched in the womb.
Bhava is also intricate; as much as true/real rasa. Bhava is feeling, it is e-motion, energies in motion. Kinetic energies with a sensor to interpret them. Its called bhava (the feelings in your system are really energy identifiers-as well as interpreters), but most often we do not see them as that. Bhava when truly appreciated and noticed, opens up wonders within this universe of possibilities.
Bhava in laymen terms is the feeling~mood~ of ones existence. But search the root word (this is the true importance of epistemology) and you find that in pali/sanskrit it has different meanings depending upon the importance one attaches to it in ones life.
The energies one faces in ones life, and the way one perceives it (because of genetic conditions-as i see it, due to past/future life karmas-ranubandhanas) molds the person to be similar. You have often heard and realized (i hope) - that looking at the world through hate~apathy brings that into your life, and looking at the world through non-seriousness similarly brings that and so on.. what i mean to ponder is that the truth of bhava is its literal meaning ' the state of becoming'
as one experiences higher levels - different levels of bhava- one becomes with them as they are- this is energetic explanation according to me (which might be very difficult to understand until you actually have experienced it- and contemplated on it)
As bhava is a more general term- the refined expression (effect due to the cause of becoming) is the rasa in ones life. Rasa in english is easily expressed as passion of ones action and being. The latter (being) is more difficult to actually visualize. Someone passionate about dancing- and their rasa out pours due to the bhava they feel towards their chosen dance. But in the state of being where action is always inconsequential; how does the cause (bhava) create the rasa (effect) ?
The true dancer; hari-krishna plays rasa-lila. He is not doing a dance. He is being the dance, the moment his rasa comes in contact with you (as you define 'you'), the bhava is uncontrollable. The energies cannot be handled, even in this day and age, if you try.. you can spot people who go into deep bhava, cry; lose their physical senses; their sense of time and space all with the 'juice' of life.
Rasa can be developed, it is potent. It is made with the bhava one beholds as theirs. Till the time one can play that rasa-lila, to another. all of life remains incomplete. The true love is missing. When the rasa is built up towards the lover, and then let loose. The bhava felt is something out of the world. Really, and if you haven't spend a single moment lost and found in that bhava or let loose the rasa (secret soma of your heart!) towards all life around you, then again as usual I ask; have you really lived? Without the essence (rasa) present, it is just a dead seed occupying space.