Mind and Body
It is also the first part of the first vipassana jhana.
Its primary obvious characteristic is that thoughts split off from seeming to be the Subject and in doing so can be observed as objective phenomena, and thus, one in this stage notices along these lines: “Ah, where as before thoughts appeared to be me, now I can see that they are just more objects.” While this is how the analytical practitioner might notice the stage, plenty of people have gotten into this insight without particularly noticing that aspect.
In this way, the meditator knows for themselves that thoughts are just thoughts, physical sensations are just physical sensations, and these are the objects that arise in the field of awareness. This is an important initial insight, and serves as the basis for subsequent insights, the next being Cause and Effect.
Mind and Body has the feeling tone of being very pleasant, like a nice opening of the mind. This tends to be much more pronounced the first time it arises, and this pleasant aspect tends to rapidly fade.
Many have experienced this stage of insight spontaneously, and it can often arise in such instances as listening to beautiful music, watching a beautiful sunset, and other pleasant activities that involve steady and natural concentration, though those who experience it at those times are unlikely to have the specific insights noted above that might occur to the analytical or technical meditator.
The standard instructions for attaining this stage are different in the various insight traditions. However, some degree of concentration and investigation of sensate reality is generally called for, though it can arise naturally during a large number of practices, from physical disciplines such as hatha yoga to more direct approaches, such as Mahasi Sayadaw based noting practices.