Dharana, the sixth limb of the Yoga philosopher Patanjali`s Ashtanga Yoga, literally means `immovable concentration of the mind`. The essential idea is to hold the concentration or focus of attention in one direction. This is not the forced concentration of, for example, solving a difficult mathematics problem; rather dharana is a form of closer to the state of mind, which could be called receptive concentration.
In practicing dharana, conditions are created for the mind to focus its attention in one direction instead of radiating out in a million different directions. Deep contemplation and reflection usually creates the right conditions, and the focus on a single chosen point becomes more intense. Concentrative meditative techniques encourage one particular activity of the mind, and the more intense it becomes the more the other preoccupation of the mind cease to exist.
The objective in dharana is to steady the mind by focusing its attention upon some stable entity. Before retracting his senses, on may practice focusing attention on a single inanimate object. After the mind becomes prepared for meditation, it is better able to focus efficiently on one subject or point of experience. Now if the yogi chooses to focus on the center (chakra) of inner energy flow, he/she can directly experience the physical and mental blocks and imbalances that remain in his or her system. This ability to concentrate depends on excellent psychological health and integration and is not an escape from reality, but rather a movement towards the perception of the true nature of the Self.