@Geoff-Allen, I'd also recommend directly studying the various suttas for yourself, where Lord Buddha taught the necessary, detailed steps to attain the achievement of the four main meditative jhanic states, e.g.
AN 4.41 &
MN 118, etc.
These are quotes (in
red) from the scriptural texts, with my understanding of the quote (in italics) right after each one; maybe it will help you get started:
1.
"gone to the forest or to the root of a tree or to an empty hut, sits down; having folded his legs crosswise, set his body erect," (from MN 118) -
This is the initial setup. One finds a secluded place to meditate, sits properly [to align the chakras and their energies and/or allows the free flow of energy between the brain and the body, IMO] ...
2. "
withdrawn from sensuality ..." (from AN 4.41) -
The meditator thus isolates himself from obvious external sensual experiences which comes through the five senses, and no longer focuses internal attention on any remaining sensory input from the five senses ...
3. "
withdrawn from unskillful qualities ..." (AN 4.41) -
Additionally, he does not pay attention to various unskillful internal qualities produced by the sixth sense (the mind, e.g. unskillful thoughts or emotions) ...
4. "
and established mindfulness in front of him, ever mindful he breathes in, mindful he breathes out." (MN 118) -
He mindfully focuses his attention on his breathing at the tip of his nose (if he chooses breathing as his meditation subject);
5. "
Breathing in long, he understands: ‘I breathe in long’; or breathing out long, he understands: ‘I breathe out long.’ Breathing in short, he understands: ‘I breathe in short’; or breathing out short, he understands: ‘I breathe out short.’ He trains thus: ‘I shall breathe in experiencing the whole body of breath’; he trains thus: ‘I shall breathe out experiencing the whole body of breath.’ He trains thus: ‘I shall breathe in tranquillising the bodily formation’; he trains thus: ‘I shall breathe out tranquillising the bodily formation.’ “He trains thus: ‘I shall breathe in experiencing rapture’; he trains thus: ‘I shall breathe out experiencing rapture.’ He trains thus: ‘I shall breathe in experiencing pleasure’; he trains thus: ‘I shall breathe out experiencing pleasure.’ He trains thus: ‘I shall breathe in experiencing the mental formation’; he trains thus: ‘I shall breathe out experiencing the mental formation." (MN 118) -
He focuses on the qualities of the breath; as he first begins his meditation, the breath is long (deep), and he notices it is so. As he relaxes into the meditation, the breath becomes shorter, and he notices it is so. After a while, the breath becomes too subtle to focus on, so he purposefully directs his focus (note how "I breathe" and "understands" changes to "I shall breathe" and "trains thus") on the whole process of breathing - the "whole body of breath". Then, as the mind settles even further, he purposefully focuses on using the breath to calm the restlessness of the body, "tranquillising the bodily formation". The mind is then directed to focus on the pleasant feelings generated as a result of a breath-calmed body; as he focuses on that pleasant feeling, it grows, suffusing the body and mind with a feeling of piti ("experiencing rapture" - the result of dopamine & norepinephrine increases in the brain?). Sukha ("experiencing pleasure" - the brain releases opioids?) also grows as a result of withdrawl of consciousness from the five material senses. Residual thoughts and emotions ("mental formations") are observed, but do not control the consciousness.
6. In such a way he "
enters & remains in the first jhana: rapture & pleasure born from withdrawal, accompanied by directed thought & evaluation." (AN 4.41) -
He thus arrives at the first jhana, feeling rapture and pleasure, with residual thoughts remaining.
The first jhana is described as corresponding to the
plane of existence for the lower Brahma gods. They dwell for up to an aeon in this state.
The second, third, and fourth jhanas are more refined and sublime states; no doubt you can read the suttas and learn how to achieve them rapidly! After reaching the fourth jhana, the meditator faces two options - to 1. continue deepening the sublime meditative states with the four "higher" arupa-jhanas, or 2. to dwell in the fourth jhana in order to progressively purify the mind; this is done in order to either 2a. progress to wisdom/insight meditation where he uses his purified mind as a tool to gain direct knowledge and insight into the nature of existence, the law of kamma, etc. or 2b. to use the purified mind to gain access to various psychic powers.
The reason the "higher" four arupa-jhanas cannot be used for wisdom/insight meditation is because the focus of consciousness is eventually eliminated as one reaches the arupa-jhanas, so that focus can no longer be used to investigate nature, reality, kamma, etc. Investigation into these subjects using wisdom/insight meditation is required to achieve nibbana; this happens because - once someone observes for himself the laws of reality, kamma, etc. - he naturally grows dispassionate towards these things which causes him to suffer and binds him to samsara, leading him into the final goal of nibbana.
