2-58

यदा सम्हरते चायम् कूर्मोऽङ्गानीव सर्वशः ।
इन्द्रियाणि इन्द्रियार्थेभ्यः तस्य प्रज्ञा पर्थिष्ठिता ॥ ५८ ॥

yadA samharate cAyam kUrmo'GgAnIva sarvazaH |
indriyANi indriyArthebhyaH tasya prajJA parthiSThitA || 58 ||

इव [iva] In a manner similar to कूर्मः [kUrmaH] a tortoise अङ्गानीव [aGgAnIva] withdrawing its limbs, यदा [yadA] when अयम् [ayam] this person सम्हरते [samharate] takes away इन्द्रियाणि [indriyANi] his sense organs इन्द्रियार्थेभ्यः [indriyArthebhyaH] from all their indulgences, तस्य प्रज्ञा [tasya prajJA] his consciousness प्रथिष्ठिता [prathiSThitA] is steadfast.

Even as the sense organs desire to indulge in things that are sensed by them, a person who pulls them back - like a tortoise pulling its limbs within - steadies his mind upon his Self and is also situated firm in wisdom .

Thus, there are four types of people who are engaged in cultivating true knowledge. This engagement can be achieved progressively, as illustrated in the verses above.

Now, the Lord says that staying engaged in this way is tough, He proceeds to describe the means by which it can be achieved.