The Nirvana Man
Life is a stormy affair. The Nirvana man/woman (recently the completely screwed down Fasting Buddha) has withdrawn to (i.e. liberated himself into) the eye of the storm. There he/she is blissfully at ease and cool.
The storm of life is a sheer endless sequence of mini storms, that is to say, of (survival) problems to be resolved. To resolve them he/she invests energy. Each time he/she resolves a problem he/she releases the energy he/she had previously invested in its resolution. That energy, released/liberated as a rush or surge, is experiened as happines (or joy or bliss and so on; it actually feels like the rapturous freedom experienced when surfing the edge of a wave). It’s when (the storm of) joy fades that nirvana, calmness ensues.
If and when a (indeed, any) storm (read also: turbulence, mental, physical or emotional) ends or one withdraws from a (i.e. any) storm, that’s when the zero (≈ 0) state is recovered, meaning that calmness, i.e. nirvana, ‘waits’ before and after a (i.e. any) storm.
Sadly the Buddha made an almighty big deal out of a very common biological experience.* But then, he had resolved a very very big and powerful problem which resulted in an equally powerful (freedom, joy and) calmness experience.
There are 2 nirvanas. Nirvana 1 happens if and when a local (i.e. relative)(survival) problem (i.e. a mini storm) is solved. Nirvana 1 is a very common, usually low intensity experience. It happens a thousand times a day, that is to say, every time a problem is solved or an obstacle overcome. It can be deliberately engineered at various intensities by resolving a true or a false problem suitably tweaked. During nirvana 1 the Nirvana man/woman ‘waits’ @ (a relative) rest (i.e. on ‘standy by’ or in a relative ‘sleep state’) because he/she does not respond (or contend).
Nirvana 2, called parinirvana, happens if and when the whole (or absolute) survival problem, as endless sequence of mini-storms is resolved, that is to say, by death.
@ (everyday) nirvana 1 a person (to wit, a conditioned appearance) has become liberated from a particular world (or indeed, from relativity, i.e. from an aspect of Samsara). @ Pari-nirvana (nirvana 2) a person becomes wholly liberated from the (storm) of the world/relativity (i.e. of Samsara), hence ceases completely as a person though leaving some (karmic) residue.
*... Early Buddhism describes bio- or gaia-logical transformations. There is in early Buddhism no concept of the ‘spiritual’. Buddhism was not and is not a ‘spiritual path,’ notwithstanding the verbose nonsense put out by Tibetan Tantrics.