|Chapter 2||The Eternal Reality of the Soul's Immortality||Verse 66|
Rudra Vaisnava Sampradaya:
Lord Krishna now reveals the controlling of the senses as a means of attaining spiritual intelligence in a converse way. The Lord states that one with an uncontrolled mind can never possess spiritual intelligence even if well versed in the Vedic scriptures and the teachings of the bona-fide preceptor in the line of Vedic disciplic succession in one of the four authorised Vaisnava sampradaya's. Why is this true? Because with an uncontrolled mind it is not possible to have spiritual intelligence, without spiritual intelligence one cannot meditate and without meditation it is not possible to realise the Ultimate Truth. So one who has an uncontrolled mind is bereft of this, for one who cannot meditate, who is unable to enlighten themselves within there is no peace and where there is no peace how can there be happiness.
Brahma Vaisnava Sampradaya:
Lord Krishna is explaining the defects due to the absence of happiness as referred to in this verse. Without being happy there is no possibility of concentration of the mind. Without concentration of the mind there can be no meditation and without meditation it is not possible to have inner awakening or soul-cognition. Therefore it has been declared that these things are not possible for one without concentration. Santih or peace refers also to liberation. Santi, moksa or liberation and nirvana all have a similar meaning denoting termination of the samsara or worldly existence.
Sri Vaisnava Sampradaya:
One who is unable to concentrate and focus their mind in meditation on Lord Krishna is known as ayukta devoid of spiritual intelligence. One who attempts to control their senses by their own efforts without securing the grace of the Supreme Lord merited by devotion. To these living entities no clear, definitive illumination in consciousness can develop; ergo , because one will not be able to internally realise the ultimate reality of the Supreme Lord through the medium of the eternal soul as having name, form, qualities, pastimes, abode and sweetness. Thus without being able to comprehend and contemplate on the nature of the eternal soul there can be no tranquillity. Nor is it possible to dispel the compulsive urge and inclination to experience sensual objects. To those who are not tranquil, who are addicted to sensual objects and who are submerged in sense gratification; how can they ever possibly attain eternal blessedness and transcendental bliss. Again as stated previously are the disastrous consequences that result in the inability to govern the tempestuous senses.
Kumara Vaisnava Sampradaya:
In order to strengthen the previous verse Lord Krishna points out all the contrary results incurred by one with an uncontrolled mind. One who has not subdued their senses by controlling their mind is bereft of determinative resolve. The intellect of one with spiritual intelligence determines the truth ascertained in the Vedic scriptures. It is not possible for an undisciplined living entity to have belief of the calibre necessary to contemplate matters relating to the ultimate truth. Without having understanding of God there is no peace and also no end to attachment for sensual objects. How can there possibly be permanent happiness which is inexhaustible and unaffected not in the least by sorrow if one is lacking peace of mind. Although material happiness is surely derived by experiencing worldly objects, the deceptive results of this perilous interaction is very succinctly summed up subsequently in verse 38 of the final chapter of Bhagavad-Gita.