Srimad Bhagavad-Gita :
Chapter-5. ( Karma-sanyasa-yogam )
Gita prescribes with few changes whatever said in Veda-s, on the procedure and steps of Sadhana.
Sri Vedavyasa Maharishi during Rishi's period presented the secrets of Vedik-informations before the people of those days in a simple way.
It is not correct to address this as a Adhyatmic revolution as criticism by some so called self-appointed scholars.
Revolution is by discarding or deleting or destroying old sampradayam / customs, and reinstalling the revolutionary customs in place of that, but, hence it is not wise to say that Sri Vyasa Maharishi had done a revolutionary act as by the present day scholars view.
To be continued ....