Daily Reading: Bhagvad Gita As it is- Page-92

Bg 2.57

yaḥ sarvatrānabhisnehas
tat tat prāpya śubhāśubham
nābhinandati na dveṣṭi
tasya prajñā pratiṣṭhitā

Translation: 

In the material world, one who is unaffected by whatever good or evil he may obtain, neither praising it nor despising it, is firmly fixed in perfect knowledge.

Purport: 

There is always some upheaval in the material world which may be good or evil. One who is not agitated by such material upheavals, who is unaffected by good and evil, is to be understood to be fixed in Kṛṣṇa consciousness. As long as one is in the material world there is always the possibility of good and evil because this world is full of duality. But one who is fixed in Kṛṣṇa consciousness is not affected by good and evil, because he is simply concerned with Kṛṣṇa, who is all-good absolute. Such consciousness in Kṛṣṇa situates one in a perfect transcendental position called, technically, samādhi.

Bg 2.58

yadā saṁharate cāyaṁ
kūrmo ’ṅgānīva sarvaśaḥ
indriyāṇīndriyārthebhyas
tasya prajñā pratiṣṭhitā

Translation: 

One who is able to withdraw his senses from sense objects, as the tortoise draws its limbs within the shell, is firmly fixed in perfect consciousness.

Purport: 

The test of a yogī, devotee or self-realized soul is that he is able to control the senses according to his plan. Most people, however, are servants of the senses and are thus directed by the dictation of the senses. That is the answer to the question as to how the yogī is situated. The senses are compared to venomous serpents. They want to act very loosely and without restriction. The yogī, or the devotee, must be very strong to control the serpents – like a snake charmer. He never allows them to act independently. There are many injunctions in the revealed scriptures; some of them are do-not’s, and some of them are do’s. Unless one is able to follow the do’s and the do-not’s, restricting oneself from sense enjoyment, it is not possible to be firmly fixed in Kṛṣṇa consciousness. The best example, set herein, is the tortoise. The tortoise can at any moment wind up its senses and exhibit them again at any time for particular purposes. Similarly, the senses of the Kṛṣṇa conscious persons are used only for some particular purpose in the service of the Lord and are withdrawn otherwise. Arjuna is being taught here to use his senses for the service of the Lord, instead of for his own satisfaction. Keeping the senses always in the service of the Lord is the example set by the analogy of the tortoise, who keeps the senses within.