The Seven Factors of Enlightenment

1 . . . Mindfulness
2 . . . Investigation of Phenomena
3 . . . Energy
4 . . . Rapture
5 . . . Tranquility
6 . . . Concentration
7 . . . Equanimity

The way to enlightenment starts with mindfulness. Mindfulness clears the ground for insight into the nature of things by bringing to light phenomena in the now, the present moment, stripped of all subjective commentary, interpretations, and projections. Then, when mindfulness has brought the bare phenomena into focus, the factor of investigation steps in to search out their characteristics, conditions, and consequences. Whereas mindfulness is basically receptive, investigation is an active factor which unflinchingly probes, analyzes, and dissects phenomena to uncover their fundamental structures.

The work of investigation requires energy, the third factor of enlightenment, which mounts in three stages. The first, inceptive energy, shakes of lethargy and arouses initial enthusiasm. As the work of contemplation advances, energy gathers momentum and enters the second stage, perseverance, wherein it propels the practice without slackening. Finally, at the peak, energy reaches the third stage, invincibility, where it drives contemplation forward leaving the hindrances powerless to stop it.

As energy increases, the fourth factor of enlightenment is quickened. This is rapture, a pleasurable interest in the object. Rapture gradually builds up, ascending to ecstatic heights: waves of bliss run through the body, the mind glows with joy, fervor and confidence intensify. But these experiences, as encouraging as they are, still contain a flaw: they create an excitation verging on restlessness. With further practice, however, rapture subsides and a tone of quietness sets in signalling the rise of the fifth factor, tranquility. Rapture remains present, but it is now subdued, and the work of contemplation proceeds with self-possessed serenity.

Tranquility brings to ripeness concentration, the sixth factor, one-pointed unification of mind. Then, with the deepening of concentration, the last enlightenment factor comes into dominance. This is equanimity, inward poise and balance free from the two defects of excitement and inertia. When inertia prevails, energy must be aroused; when excitement prevails, it is necessary to exercise restraint. But when both defects have been vanquished the practice can unfold evenly without need for concern. The mind of equanimity is compared to the driver of a chariot when the horses are moving at a steady pace: he neither has to urge them forward nor to hold them back, but can just sit comfortably and watch the scenery go by.  Equanimity has the same "on-looking" quality. When the other factors are balanced the mind remains poised watching the play of phenomena.

Bhikkhu Bodhi, in The Noble Eightfold Path