The subject matter of Bhagavad-gītā is to know five things, to know what are these living entities, what is God, what is nature, and what is time, and what is work.
Revatīnandana: "The yoga system instructed in this chapter is called sanātana-yoga, or eternal activities performed by the living entity. This yoga has two divisions of action, called sacrifices. One is called sacrifice of one's material possessions, and the other is called knowledge of self, which is pure spiritual activity. If sacrifice of one's material possessions is not dovetailed for spiritual realization, then such sacrifice becomes material. But one who performs such sacrifices for a spiritual objective or in devotional service, makes a perfect sacrifice. When we come to spiritual activities, we find that these are also divided into two: namely, understanding of one's own self or one's constitutional position, and the truth regarding the Supreme Personality of Godhead. One who follows the path of the Bhagavad-gītā as it is, as it is..."
Prabhupāda: "As it is."
Revatīnandana: "...of the Bhagavad-gītā as it is can very easily understand these two important divisions of spiritual knowledge. For him there is no difficulty in obtaining perfect knowledge of the self as part and parcel of the Lord."
Prabhupāda: Because the subject matter of Bhagavad-gītā is to know five things, to know what are these living entities, what is God, what is nature, and what is time, and what is work. These five subject matters are there: God, the living entities, the nature, the time, and the work. These things are there.