Concentration is an exclusive gift of the mind, a mechanical thought power to sustain and fix closely an idea. This gift has not anything to do with kindness of the heart or spiritual aspirations of the soul.
By Concentration your mental matter does not acquire any form, but adopts only one form.
Concentration is made in two ways: one is objective and other subjective. One, as expression of the will, acts on a sense or determined form; other, as state of abstract mental consciousness, is over all senses.
First exercise: During hours of the morning, on an isolated and calm place, the student should be seated, straight his body and his head, and the hands relaxed on his knees; slowly he shall vocalize some holy formula or a constructive words that he prefers, imagining a golden yellow color all around him.
Every rule aiming at achieving the Divine Union has its exception.
Certain souls never knew Meditation and others ignored Concentration but reached a perfect Union with God. Any indiscriminate imposition of these rules on everybody is to ignore that every soul is a separate world and needs its own rules and an especial development to reach the goal.
Here you shall find in detail main postures used in meditation and concentration.
For meditation, you should use the “mental seated posture” described above, but with your arms freely hanging from your shoulders at each side of the body.