In a state of deep concentration, withdrawn from the senses, one can attach the mind to a single object or idea, deepening one’s sense of unity.
Focusing on something like the cadence of a steadily dripping faucet, the calm mind can become fully absorbed in concentration. Free from the distractions of the senses (pratyahara), one rises above the chaos of thoughts and devotes the mind to focus on a single object or repeating idea, like a mantra.
Reaching a state of Dharana comes from the discipline involved in mastering the previous subjects.
When one can enter into a state of complete concentration at will, advancement involves softening one’s self even further.