13.4-5 Tat Ksetram etc. Rsibhih etc.  Why it modifies : due to what this  [Field] suffers  modification.  Collectively : not at all separately  (one by one).  [The Bhagavat]  decides all the estions in a general way.  Of course, many a time in many a way this has been declared by the seers and by the scritpures. But, let Me (the Bhagavat)  explain this collectively (briefly).