The Visuddhimagga describes all of the jhānas as complete absorption states. There are no body sensations, no sounds are heard, there is not even the sense of time passing.1 The vitakka and vicāra mentioned in the description of the first jhāna are no longer understood as "thinking and examining" but rather as "initial and sustained attention [to the meditation object];" one-pointedness has also been added as an additional factor of the first jhāna. This is the same understanding as found in the Abhidhamma. In order to enter such a deep state, the concentration preceding the entry into the jhānas, now officially called "access concentration," requires a depth strong enough to generate a nimitta – see the previous appendix for more information on Nimitta.

By the time of the Visuddhimagga, the jhānas had become redefined to such profoundly deep states of concentration that it was extremely difficult to learn them. In fact the Visuddhimagga says the following:

[The] preliminary work is difficult for a beginner and only one in a hundred or a thousand can do it. The arousing of the nimitta is difficult for one who has done the preliminary work and only one in a hundred or a thousand can do it. To extend the nimitta when it has arisen and to reach absorption is difficult and only one in a hundred or a thousand can do it."2

The most prominent access method found in the Visuddhimagga is meditation on a kasiṇa – a color disk about the size of a dinner plate. The Visuddhimagga gives a quite detailed description of how this is done,4 along with discussing other access techniques as well.5 It is very interesting that kasiṇa meditation becomes the most important access method in the Visuddhimagga. The word "kasiṇa" does appear in the suttas – 10 kasiṇas are listed at DN 33.3.3.2 and MN 77.24. But nowhere else in these two Nikāya, where the jhānas are repeatedly mentioned, are kasiṇas mentioned.6

Since one who is experiencing the Visuddhimagga jhānas is completely absorbed in the experience, the factors of the jhānic experience can only be determined by reflecting back on the experience after one leaves the jhāna. One does not move between jhānas directly: instead of going from access concentration (AC) into the first jhāna, then the second (i.e., AC-1-2-3-4-5-6-7-8), one must return to access concentration between jhānas (i.e., AC-1-AC-2-AC-3-AC-4 etc.). And of course since one is totally absorbed while in a jhāna, it is impossible to do any insight practice while in the jhānas – one always has to exit the jhānas before beginning any sort of insight practice.

These very deep states do indeed generate a mind that is super concentrated, very pure and bright, truly malleable, wieldy and steady, and strongly imperturbable. This is a very powerful mind state for undertaking insight practice. But it has this very serious drawback of being extremely difficult to access. For a given individual, it is also possible that the effort to reach such a state may push one past the point of diminishing returns, in that the time spent working to enter such a state could perhaps have been more productively used to generate a lesser level of concentration and then begin insight meditation practice with that level of concentration.

It does seem that if you have both the skill necessary to learn the Visuddhimagga jhānas and the lifestyle that affords you the time to actually enter these jhānas, they provide an excellent jumping off place for beginning insight meditation. But most lay people don't frequently have weeks and months of nothing else to do but silently meditate – and that seems to be a requirement, even for those who do learn the Visuddhimagga jhānas relatively easily.

Unfortunately this Visuddhimagga description of what constitutes a jhāna has persisted as the orthodox Theravādan understanding of the jhānas into the 20th and 21st centuries – for the most part. There is nothing in this understanding that would constitute "wrong concentration;" it's just that this understanding is quite impractical and very different from the Buddha's understanding of the jhānas.

This brief overview of the Visuddhimagga jhānas is in no way complete. Luckily there are a number of excellent books available that do provide an in-depth look at the Visuddhimagga Jhānas. Both Shaila Catherine's Focused and Fearless and Stephen Snyder and Tina Rasmussen's Practicing the Jhānas are very readable books. They are both based on the teachings of Ven. Pa Auk whose teachings, not only of the jhānas, but also of insight, are based on what is found in the Visuddhimagga. Ven. Pa Auk also has a quite good book entitled Knowing and Seeing which is even available for free download from http://www.buddhanet.net/pdf_file/know-see.pdf. Richard Shankman's The Experience of Samādhi gives an excellent overview of both the Sutta Jhānas and the Visuddhimagga Jhānas. Ajahn Brahmavamso teaches jhānas that use a nimitta as access to absorption states, although he claims not to be teaching in the style of the Visuddhimagga. He too has an excellent book entitled Mindfulness, Bliss, and Beyond.

Of course, if you are really interested in learning about the Visuddhimagga jhānas, the Visuddhimagga itself has been excellently translated into English by Ven. Nyanamoli. And although like the rest of the Visuddhimagga, the chapters on concentration (III - XIII) are not an easy read, they do contain valuable information on what has come to be the orthodox Theravādan understanding of the jhānas. You can freely download a copy of the Visuddhimagga from http://www.accesstoinsight.org/lib/authors/nanamoli/PathofPurification2011.pdf.

1. Vsm IV.79ff. See also Pa Auk, 2000, p. 102.
2. Vsm XII.8
3. E.g. Sāriputta in MN 111, SN 28; Mahāmoggallāna in SN 21.1, SN 40.1-8; Anuruddha in MN 31 (along with Nandiya and Kimbila), SN 52.21; Vacchagotta in MN 73; monks in general in DN 22, MN 141, SN 36.31, 46.54, 48.10. The phrase "He obtains/gains at will, without trouble or difficulty, the four jhānas" occurs at MN 6.9, MN 53.6, MN 108.17, MN 119.36, SN 21.4 and over 20 times in the AN.
4. Vsm IV.1-33, pages 113-122
5. Vsm III-XIII, pages 81-430
6. Kasiṇas are not mentioned at all in the SN. The 10 kasiṇas do occur at AN 1.455-464 and AN 10.25, 26 & 29, but not in connection with the jhānas. See Polak, 2011, pp 127-130 for a more detailed discussion of kasiṇas in the suttas.