Jīva Gosvāmī’s philosophical magnum opus, the Ṣaṭ Sandarbha (“six treatises) can be considered as the most conclusive and important work on Indian theology and philosophy (darśana) that answers all questions about Absolute Reality in a very systematical way.
Tattva Sandarbha is the first book of the Ṣaṭ Sandarbhas. It discusses the Reality (tattva) that is the ultimate subject to be understood and realized. It also offers a brief overview of Gauḍīya Vaiṣṇava ontology, on which its theology is based. Tattva also means “essence,” and thus Tattva Sandarbha provides the essence of what is to be elaborated upon in the rest of the Sandarbhasand serves as an introduction to them. This book can be divided into two parts, pramāṇa and prameya. The first deals with epistemology (pramāṇa), or the means of valid knowing. In it, Jīva Gosvāmī establishes the Bhāgavata Purāṇa as the foremost source of knowledge and vision of Reality. Tattva Sandarbha provides the epistemological viewing frame through which Śrīmad Bhāgavata is established as the means of valid knowing of Ultimate Reality and Bhagavān as the supreme object of divine love.
If you chant one round in Vrindavan it is equal to chanting 100 rounds outside. It is not just one-sided though. You have to remember that if you make a mistake here, it is also 100 times. If you perform a sinful activity here, then there is no solution for that. You must suffer heavily. If you do some mistake here it implicates you heavily. If you do something good here then you will benefit.