Devotional service is the constitutional activity of the soul. It means engaging all senses in the service of the Supreme with love and devotion. The Bhagavad-gita (6.47) teaches that the greatest yogi is one who thinks of the Lord always, and (9.34) declares that devotional service is the highest path. The Bhagavad-gita (12.6-7) explains that pure devotion is unmotivated and uninterrupted, and (18.65) states that bhakti surpasses all other paths including karma (action), jnana (knowledge), and yoga (meditation). The Nectar of Devotion (Chapters 1-4) elaborates that love of God is the highest achievement.