Sometimes, even after exhaustively researching Folio, also know as the Bhaktivedanta Vedabase, it is difficult to determine what Srila Prabhupada thought about a particular subject. Pradyumna prabhu, in a letter written to the HH Satsvarupa das Goswami on 7 August 1978 (and now made public) has pointed out that ‘sistacara’ can be as important as the ‘conclusions’ reached through careful studies of what Srila Prabhupada wrote and said. He puts it like this: “Much of the knowledge written here is not found in sastra, but is called sistacara–that which has been taught by the conduct of the past guru parampara. It has not been specifically mentioned in any sastra, but still it is accepted as authoritative because of being seen to be the conduct of previous acaryas and their disciples.”