Whole concentration speaks to a one-pointedness of mind.
Whereas mindfulness has a flexible, take-it-as-it-comes quality, concentration is like the lion’s gaze on the chosen antelope, watchful without missing a breath.
My teachers told us a story that they could usually tell in a waitress/waiter whether they had a mindfulness practice in how they put the tea cup down on their table. Once they asked a waitress if she was a meditator and she said no, but she was an advanced practitioner in archery.
Like archery, concentration involves focus on a single object. In meditation it can be the in and out your breath through the entrance of your nostrils. Can you get much more specific? There can be a lot of resistance at first to concentration because it involves letting go of your personal story, your feelings, your thoughts, the things that make me “me”. There is no place for thinking about how awesome you will look surfing in Hawaii this winter while sensing the subtle in and out of your breath through the entrance of your nostril. Is my breath hot? Is this my right nostril the air is coming through? Is my breath unusually shallow right now? Particularly laboured?
Muscles in concentration built in meditation make it possible in daily life to drop your personal story. This is not to be undervalued. To drop your personal story means your open to the countless other stories involved in the making of life, and the reality that none of them are really true or false. They are a “compost heap” as my teachers like to say. In this way whole concentration preps a person for wholeness on any other part of the path.
The third and last factor of Mental Discipline is Right Concentration, leading to the four stages of Dhyana, generally called trance or recueillement. In the first stage of Dhyana, passionate desires and certain unwholesome thoughts like sensuous lust, ill-will, languor, worry, restlessness, and skeptical doubt are discarded, and feelings of joy and happiness are maintained, along with certain mental activities. In the second stage, all intellectual activities are suppressed, tranquillity and “one-pointedness” of mind developed, and the feelings of joy and happiness are still retained. In the third stage, the feeling of joy, which is an active sensation, also disappears, while the disposition of happiness still remains in addition to mindful equanimity. In the fourth stage of Dhyana, all sensations, even of happiness and unhappiness, of joy and sorrow, disappear, only pure equanimity and awareness remaining.