SPIRIT OF BHAGAVAD GITA
The spirit of Bhagavad-gita is mentioned in Bhagavad-gita itself. It is just like this: If we want to take a particular medicine, then we have to follow the directions written on the label. We cannot take the medicine according to our own whim or the direction of a friend. It must be taken according to the directions on the label or the directions given by a physician. Similarly, Bhagavad-gita should be taken or accepted as it is directed by the speaker Himself.
The speaker of Bhagavad-gita is Lord Sri Krishna. He is mentioned on every page of Bhagavad-gita as the Supreme Personality of Godhead, Bhagavan. Of course the word bhagavan sometimes refers to any powerful person or any powerful demigod, and certainly here bhagavan designates Lord Sri Krishna as a great personality, but at the same time we should know that Lord Sri Krishna is the Supreme Personality of Godhead.
Therefore we should take Bhagavad-gita as it is directed by the Personality of Godhead Himself.