In essence the understanding is extremely simple. Bearing in mind the definitions I have sought to establish (which you can access by clicking on the underlined words), particularly the restriction we have placed on the role of conscious mental activity in limiting it to being the tool with which we satisfy our appetites, we can say:
Because A is the objective description of what happens when we satisfy an appetite (fewer neurones fire) and B is the subjective description of what it feels like when that happens and because we are talking about the same mind at the same point in time, we can derive a third statement from A and B above:
In this way we have derived the mechanics of happiness in creatures with our kind of nervous system. (Note that reducing conscious mental activity doesnot entail a reduction in the level of our awareness: that remains constant at an ordinary, every-day level.) Now if we extrapolate the relationship expressed in statement C to the extreme case we arrive at the following statement:
It is the main contention of this theory that the latter statement corresponds exactly in meaning to the statement made by Sakyamuni Buddha two and a half thousand years ago which has been translated as:
By uttering that simple statement the Buddha changed his world. Attempting a practical application of this understanding has the potential to radically alter yours. This is the knowledge which meditators have always exploited when they practised emptying their minds. This is how to gain access to the Void. This is how to realise the potential your own mind has for becoming Buddha-mind. This is how to experience Nirvana.
Here we have, encapsulated in one short sentence, the psychology of the common human goal. Thoroughly understanding it is the key to living a truly successful life. To extract the ultimate benefit from this knowledge we must fully appreciate the implications of the relationship between conscious mental activity and happiness, first theoretically and then practically.
Only then can we be certain of getting our just and proper reward for our successful actions.
When, through diligent practise, conscious mental activity is reduced to zero, no matter how temporarily, (which implies retreating through the gates of language and B O S the brain's operating system.) what remains is an awareness of all the categories of pleasures, pains, moods and emotions. Because the emotions of anger, jealousy, envy, etc. all have to be sustained by constant conscious mental activity they can, with practise, be renounced. Assuming we are not experiencing any pleasures, pains or emotions then only our mood remains - happiness.
We will then experience the bliss of the Buddhas - Nirvana.