A grantha should set forth at the beginning what its main focus is. This is called vishaya. How is the grantha going to benefit those who read it has also to be told. This is prayojana. Who is the adhikari, or the one qualified to expound on the text has also to be mentioned. Sambandha, which is the connection between vishaya, prayojana and adhikari, must also be specified.
Srimad Bhagavatam begins with three mangala slokas, said Valayapet Ramachariar in a discourse. Here the vishaya – that is the main theme of the work – is given as dharma. Vyasa was the author of the work, and it came to us through his son Suka. Vyasa tells us about dharma in this work. There are two kinds of dharma – siddha dharma and sadhya dharma. Siddha dharma is the Supreme One, Lord Narayana. Kathopanishad says that one may be a scholar, or a devotee, but it is Divine will that determines what we should receive. To attain moksha He is the means. Sadhya dharma refers to the means we use to reach Him, like bhakti yoga or Saranagati. Srimad Bhagavatam gives us more peace of mind than the study of Vedanta. It talks about the dharma of virtuous people, whose hearts are pure (nirmatsaraanaam). They are free from pride. Bhagavatam speaks nothing but the truth and adheres to facts (vaasthavam).
The Lord is not just the goal, but the means to attain that goal, and Srimad Bhagavatam shows us this.