Bhagavad-gita is the widely read theistic science summarized in theGita-mahatmya (Glorification of the Gita). There it says that one should read Bhagavad-gita very scrutinizingly with the help of a person who is a devotee of Sri Krsna and try to understand it without personally motivated interpretations. The example of clear understanding is there in the Bhagavad-gita itself, in the way the teaching is understood by Arjuna, who heard the Gita directly from the Lord. If someone is fortunate enough to understand Bhagavad-gita in that line of disciplic succession, without motivated interpretation, then he surpasses all studies of Vedic wisdom, and all scriptures of the world. One will find in the Bhagavad-gita all that is contained in other scriptures, but the reader will also find things which are not to be found elsewhere. That is the specific standard of the Gita. It is the perfect theistic science because it is directly spoken by the Supreme Personality of Godhead, Lord Sri Krsna.