Chapter 2, Verse 58
Part of 2: Sānkhya Yog — सांख्ययोगयदा संहरते चायं कूर्मोऽङ्गानीव सर्वशः। इन्द्रियाणीन्द्रियार्थेभ्यस्तस्य प्रज्ञा प्रतिष्ठिता॥
yadā sanharate chāyaṁ kūrmo ’ṅgānīva sarvaśhaḥ indriyāṇīndriyārthebhyas tasya prajñā pratiṣhṭhitā
When, like the tortoise which withdraws all its limbs on all sides, he withdraws his senses from the sense-objects, then his wisdom becomes steady.
Withdrawal of the senses is Pratyahara or abstraction. The mind has a natural,tendency to run towards external objects. The Yogi again and again withdraws the mind from the objects of the senses and fixes it on the Self. A Yogi who is endowed with the power of Pratyahara can enter into Samadhi even in a crowded place by withdrawing his senses within the twinkling of an eye. He is not disturbed by tumultuous sounds and noises of any description. Even on the battlefield he can rest in his centre, the Self, by withdrawing his senses. He who practises Pratyahara is dead to the world. He will not be affected by the outside vibrations. At any time by mere willing he can bring his senses under his perfect control. They are his obedient servants or instruments.