The qualification of bhakti, or devotional service to the Lord, is that the devotee should be free from all material contaminations and desires. This freedom is called vairāgya, or renouncement of material desires. One who engages in devotional service to the Lord according to regulative principles is automatically freed from material desires, and in that pure state of mind one can realize the Personality of Godhead. The Personality of Godhead, being situated in everyone’s heart, instructs the devotee regarding pure devotional service so that he may ultimately achieve the association of the Lord. This is confirmed in Bhagavad-gītā (10.10) as follows:

teṣāṁ satata-yuktānāṁ bhajatāṁ prīti-pūrvakam dadāmi buddhi-yogaṁ taṁ yena mām upayānti te

“To one who constantly engages in the devotional service of the Lord with faith and love, the Lord certainly gives the intelligence to achieve Him at the ultimate end.”

One has to conquer the mind, and one may do it by following the Vedic rituals and by performing different types of sacrifice. The ultimate end of all those performances is to attain bhakti, or the devotional service of the Lord. Without bhakti one cannot understand the Supreme Personality of Godhead. The original Personality of Godhead or His innumerable expansions of Viṣṇu are the only objects of worship by all the Vedic rituals and sacrificial performances.