Reading Works of the Previous Acaryas.
Srila Prabhupada: Within the past five hundred years, many erudite scholars and acharyas like Jiva Goswami, Sanatan Goswami, Vishwanath Chakravarti, Vallabhacharya, and many other distinguished scholars even after the time of Lord Chaitanya made elaborate commentaries on the Bhagavatam, and the serious student would do well to attempt to go through them to better relish the transcendental messages. (Purport to Bhag. 1.1.11.) A sincere devotee must, therefore, be prepared to hear the Vedic literature like the Upanisads, Vedanta and other literatures left by previous authorities or Goswamis for the benefit of his progress. Without hearing such literatures, one cannot make actual progress.
And without hearing and following the instructions, the show of devotional service becomes worthless and therefore a sort of disturbance in the path of devotional service. Unless, therefore, devotional service is established on the principles of sruti, smrti , purana or pahcaratra authorities, the make-show of devotional service should at once be rejected. An unauthorized devotee should never be recognized as a pure devotee. By assimilation of such messages from the Vedic literatures, one can see the all-pervading localized aspect of the Personality of Godhead within his own self constantly. This is called samadhi. (Purport to Bhag. 1.2.12.) Those in the most exalted position of devotional service and ecstasy can live with Krishna always by remembering his pastimes. Srila Viswanath Chakravarti Thakur has given us a transcendental literary work entitled Krsna- bhavanamrta, which is full with Krishna’s pastimes. Exalted devotees can remain absorbed in Krishna-thought by reading such books. Any book of Krsna-lila , even this book, Krsna , or our Teachings of Lord Caitanya , is actually solace for devotees feeling separation from Krishna. ( Krsna, p. 367.)
From KK Bindu #404: https://goo.gl/H5rpAq