A Stilled and Settled State of Mind
Shamatha (calm abiding), a stilled and settled state of mind, is more than just absorbed concentration. It is not merely a state of mind stilled of the obstacles to concentration and settled single-pointedly on an object or in a particular state. In addition, it has a further mental factor accompanying it: a sense of physical and mental fitness (pliability, flexibility).
A sense of physical and mental fitness is the mental factor of feeling totally fit to do something – in this case, remain totally concentrated on anything. It is both exhilarating and blissful, but in a nondisturbing way.
Of the two main types of meditation, discerning (analytical meditation) and stabilizing (fixing meditation), shamatha is an example of the latter.
As a side product, shamatha brings extrasensory awareness (advanced awareness), such as the ability to see and hear things at a great distance and to be aware of other's thoughts. In Lamp for the Path to Enlightenment, the late tenth-century Indian master Atisha emphasizes the importance of gaining these abilities to be better able to help others.
An Exceptionally Perceptive State of Mind
By itself, shamatha does not have the mental factor of subtle discernment (scrutiny, analysis). Subtle discernment is an active understanding of the fine details of the nature of something, having scrutinized them thoroughly. It does not imply verbal thinking, although it may be induced by verbally thinking. Thus, of the two main types of meditation, discerning and stabilizing, vipashyana emphasizes the former.
When, on top of shamatha, the mental factor of subtle discernment and a second sense of physical and mental fitness are present, the state of mind becomes vipashyana (Pali: vipassana, special insight), an exceptionally perceptive state of mind. The additional sense of fitness is the sense of feeling totally fit to discern and understand fully the subtle details of anything.
If a state of mind is one of vipashyana, it is pervasive that it is a state of the joined pair: shamatha and vipashyana. In a joined pair, one of the items – in this case, shamatha – is attained first, and then the second item – in this case, vipashyana – is joined to it. Therefore, although we may work on vipashyana before attaining shamatha, we cannot actually attain vipashyana without having first attained shamatha.