The central point of yoga is to control the mind, bringing it to a state where it is completely calm and stable. Our mind separates us from the Lord. It always disturbs us and creates so many problems. The mind is stronger than intelligence, but buddhi is higher than the mind, so it is supposed to control it.

However, because our senses are so strong, intelligence cannot control them. It was easy for ancient people to control their mind, because their intelligence was very strong. From a very young age, they knew what dharma and adharma are. If we study the scriptures, vivek sakti will awaken in our intelligence. But if we read the scriptures alone, it will not have much of a positive effect.

The only way to develop buddhi to such an extent that it will be able to control the mind is to have sadhu-sanga. The key to controling the mind is to chant Hare Krishna with humility, and humility comes only from intelligence.