The concept of "right concentration"

Hi.

The eighth factor of the path is right concentration, in Pali samma samadhi.

And what is right concentration? There is the case where a monk — quite withdrawn from sensuality, withdrawn from unskillful (mental) qualities — enters & remains in the first jhana: rapture & pleasure born from withdrawal, accompanied by directed thought & evaluation. With the stilling of directed thoughts & evaluations, he enters & remains in the second jhana: rapture & pleasure born of composure, unification of awareness free from directed thought & evaluation — internal assurance. With the fading of rapture, he remains equanimous, mindful, & alert, and senses pleasure with the body. He enters & remains in the third jhana, of which the Noble Ones declare, 'Equanimous & mindful, he has a pleasant abiding.' With the abandoning of pleasure & pain — as with the earlier disappearance of elation & distress — he enters & remains in the fourth jhana: purity of equanimity & mindfulness, neither pleasure nor pain. This is called right concentration.

- Magga-vibhanga Sutta

It's not so much WHAT you do as HOW you do it.
In general terms, Right Concentration means establishing the "Right mind".
But what is "left mind"?

Mtfbwy
Fugen