“One who knows how to observe the mind with the mind is the best of contemplatives” -The questions of King Dewa Sutra
Mindfulness is our capacity to use the mind to observe the mind. The thinking mind is normally oriented toward action and doing. Through the processes of desire and aversion, action and reaction, the ego navigates reality.
The ego experiences the world in terms of stimuli that is both pleasurable and painful. This stimuli emerges from inside of the individual in the form of internal stimuli (feelings, dreams, fantasies). It is also experienced outside the individual in terms of sensations from the world of objects. The ego provides an experience of constancy and continuity within the flux of this stimuli, but does so by struggling against the feelings, fantasies and sensation.
The ego registers the flow of sensations in terms of desire and aversion. In this way the ego is continually evaluating the gap between how things are and how we want them to be (an ideal). And so, it continually struggles toward that which is pleasureful and desired, and away from that which is perceived as un-pleasurable and to be avoided.
When we recognize the ego in its continual action and reaction we open to awareness of being that lies at the root of action. Being and action are in a dialectic relationship. Through awareness of this relationship, we can come to experience the way that these two aspects of the mind relate to each other. From this awareness we can open more fully to the pleroma of internal and external experience.