Here a monk lives contemplating the body in the body, ardent, clearly
conscious and mindful, having overcome, in this world, covetousness and
dejection; he lives contemplating feelings in feelings, ardent, clearly
conscious and mindful, having overcome, in this world, covetousness and
dejection; he lives contemplating consciousness in consciousness, ardent,
clearly conscious and mindful, having overcome, in this world, covetous-
ness and dejection; he lives contemplating mental objects in mental ob-
jects, ardent, clearly conscious and mindful, having overcome in this
world, covetousness and dejection.

    And how, monks, does a monk live contemplating body in the body?  Here
a monk, having gone to the forest, sits down cross-legged keeping his body
erect and setting up mindfulness in front of him.  Mindful he breathes in,
mindful he breathes out.  Breathing in long, he knows, "I breathe in long."
Breathing out long, he knows, "I breathe out long."  Breathing in short,
he knows, "I breathe in short."  Breathing out short, he knows, "I breathe
out short."  "Experiencing the whole body I shall breathe out," thus he
trains himself....

    And further, a monk knows when he is going, "I am going"; he knows
when he is standing, "I am standing"; he knows when he is sitting, "I am
sitting"; he knows when he is lying down, "I am lying down"; or just as
the body is disposed so he knows it....

    And further, a monk reflects on this very body enveloped by the skin
and full of manifold impurity from the soles up and from the crown of the
head down, thinking, "There are in this body: hair of the head, hair of
the body, nails, teeth, skin, flesh, sinews, bones, marrow, kidney, heart,
liver, membranes, spleen, lungs, bowels, intestines, mesentery, feces,
bile, phlegm, pus, blood, sweat, fat, saliva, mucus, synovic fluid,
urine."...

    And further, if a monk sees a body dead for one day, or two or three,
swollen, discolored, decomposing, thrown aside in the cemetery, he app-
lies this perception to his own body, "Truly, this body of mine, too, is
of the same nature, it will become like that and will not escape it."...

    And how, monks, does a monk live contemplating feelings in feelings?

    Here a monk when experiencing a pleasant feeling knows, "I experience
a pleasant feeling"; when experiencing a painful feeling knows, "I exper-
ience a painful feeling"; when experiencing a feeling that is neither
pleasant nor painful knows, "I experience a neither pleasant nor painful
feeling."...

    And how does a monk live contemplating consciousness in consciousness?

    Here, monks, a monk knows the consciousness with craving as with crav-
ing; the consciousness without craving as without craving; the conscious-
ness with anger as with anger; the consciousness without anger as without
anger; the consciousness with ignorance as with ignorance; the conscious-
ness without ignorance as without ignorance... the freed state of con-
sciousness as the freed state; the unfreed state of consciousness as the
unfreed....

    And how does a monk live contemplating mental objects in mental ob-
jects?

    Here, monks, a monk lives contemplating mental objects in the mental
objects of the five hindrances.  When sense desire is present, a monk
knows, "There is sense desire in me", or when sense desire is not present
he knows, "There is no sense desire in me."  He knows how the arising of
the non-arisen sense desire comes to be; he knows how the abandoning of
the arisen sense-desire comes to be; he knows how the non-arising in the
future of the abandoned sense desire comes to be.  When anger is present,
he knows... when sloth and torpor is present, he knows... when restless-
ness and worry are present, he knows... when doubt is present, he knows...

    Truly, monks, whoever practices these Four Settings up of Mindfulness
for seven years, then one of two results may be expected by him: highest
knowledge here and now or, if some remainder of clinging is yet present,
the state of non-returning.

                   Majjhima Nikaya i.55-63, Satipatthana Sutta