(Kadamba Kanana Swami, September 2013, Cape Town, South Africa, Srimad Bhagavatam 8.20.12)
It is said that as long as Krsna was gracing the planet; everything was auspicious, opulent and widely available. But when Krsna left the planet then everything changed and not only did natural opulence disappear but dharma-jñānādibhiḥ saha (Srimad Bhagavatam 1.3.43).
Dharma-jñānā also went with him. When Krsna left then the world was deprived of religious principles, the world was deprived of knowledge, and people sunk down into ignorance.
The Bhagavad-gita is particularly that book which cuts through ignorance because Arjuna is in ignorance. He has the bow, the gandiva, and it is gliding from his hand,
aśocyān anvaśocas tvaṁ
prajñā-vādāṁś ca bhāṣase
gatāsūn agatāsūṁś ca
nānuśocanti paṇḍitāḥ, (Bhagavad-gita 2.11)
You are mourning for what is not worthy of grief, it is stated. Arjuna is in ignorance and therefore he is reminded of the position of the soul as being eternal. He gets an explanation of the three modes of material nature. He is explained on how lust is dealing,
āvṛtaṁ jñānam etena
duṣpūreṇānalena ca, (Bhagavad-gita 3.39)
That lust covers the consciousness and covers knowledge and that is,
indriyāṇi mano buddhir
asyādhiṣṭhānam ucyate, (Bhagavad-gita 3.40)
That it is situated within the senses, within the mind and in the intelligence. So little-by-little, the Bhagavad-gita is pointing out how we are in the grip of the material energy. One learns the austerities of the body and how one has to bow down before elders and respect them. One learns the austerity of the mind and when the conditions are right, one has to be satisfied. The mind is never satisfied and always finds something that is not satisfying. With the austerity of the mind, we have to immediately cut a thought that is not ānukūlya
prātikūlyasya varjanam, (Hari-bhakti-vilasa, quoted in CC. Madhya 22.100)
Where it is ānukūlya, unfavourable, let go, just let that thought go, do not dwell on the thought! When it is favourable for the service of Krsna, then accept it. That is the way to deal with the mind – the austerity of the mind.