Day 20 Sutras 2:54 When the senses withdraw themselves from [and disregard] the objects around them and imitate, as it were, the nature of the mind stuff, this is pratyahara.
Pratyahara is the 5th limb of yoga and involves restraining the five senses. When the senses are focused outside, they constantly transfer messages to the mind and make it restless. Restraint of the senses means that instead of creating distractions and dragging the mind here and there, e.g. look at this, do you hear that, taste this, feel that, smell this...
With pratyahara, the senses withdraw themselves from what the mind is attending to and because the senses are not involved and are faithfully following the mind, the mind chatter diminishes.
As Sri Swami Satchidananda puts it: “by turning inward, they [senses] find peace by taking the form of the mind itself.”
Withdrawing the senses is another way of stilling and gaining mastery over the mind. However, this isn't an easy thing to do. That's why most people start with asana and pranayama. Even the yamas and niyamas are not so easy for people to practice. With pratyahara, sensual pleasures have to be disregarded. The less reactive you are to the information that the senses bring, the less control the senses have and you can eventually tame them completely.
