Srimad Bhagavad-Gita :
Chapter- 2. ( Samkya-yogam)
Slokam-58. ( very important slokam )
Yada samharate cayam kurmmonganiva sarvasah,
Indriyannindriyarthebhyah tasya prajna pratishthita.
yada ayam = when this yogi;
sarvasah indriyarthebhyah = altogether senses from the vishayas ( sense objects );
kurmmah amgani iva = like Tortoise ( its ) body parts ( head and limbs );
indriyanni samharate ca = ( yogi ) Withdraws ( his ) senses ( likewise tortoise );
( tada ) tasya = then his;
prajna pratishthita = consciousness ( strongly and permanently ) fixed up.
Lord Krishna gives the analogy of a turtle which withdraws its limbs inside. Similarly when one is able to keep their senses from pursuing sensual objects of mundane pleasure by withdrawing the senses inside and who also consciously reflects upon the soul within, such a one is sthita- prajna situated in the perfect knowledge of transcendent meditation. There are four stages in developing to this platform each of which develops backwards from its preceding stage. The difficulty in following this is revealed by Lord Krishna in the next slokam.
Further it is stated that when one withdraws his senses from the objects of the senses such as the ears from sound, the eyes from sight, the tongue from taste and so forth then one becomes steady in wisdom. Regarding the effortless manner in which this withdrawal of the senses is to be enacted is indicated by the example of a turtle withdrawing its limbs within its body.
Lord Krishna answers the question, How does such a one sit? With the word yada meaning when, when one is in meditation they do not let their senses go out, for example like the following of sounds by the ear and compels the organs of action to perform only the basic functions of utmost necessity. The illustration used is of the turtle which out of fear of something protects itself by drawing its limbs and head inside its shell. After the danger passes the turtle again lets out its limbs again and in a controlled manner continues on its way. In the same way one who is sthita-prajna situated in the perfect knowledge of transcendent meditation acts thus.
The test of a yogi, 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 consciousness. The best example, set herein, is the tortoise. The tortoise can at any moment wind up its organs on sensing its enemy presence and exhibit them again at any time when the danger situation removed. Similarly, the senses of the conscious persons are used only for some particular purpose in the service of the Lord and are withdrawn otherwise. 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.
To be continued ..