The Gita is a synthesis of Sankhya, Yoga (synonymous with Karma Yoga) and Vedanta (the Gyaan aspect). To these, it adds a powerful and uplifting element of Bhakti and surrender, which are not found in Sankhya or Vedanta. It is an integral path. Also, the Gita speaks of the double nature, the higher Divine Nature (Paraprakriti), while the Sakhya speaks only of Prakriti as it operates here. There is only one Purusha in the Sankhya who is primarily a Sakshi or else involved in Nature and thereby bound. The Gita speaks of three Purushas, the Uttam Purusha, beyond these two. Sankhya is in its philosophy is quite an atheistic and mechanical in the determinism. The Gita is Theistic and looks to a state beyond the three gunas that are deterministic. The only elements of Sankhya taken by the Gita is the role of the discerning intellect, Buddhi, the Witness state, the three gunas, the Self above nature and the multiplicity of souls. But there is so much more that the Gita brings in as its own unique revelation, as well as synthetic elements that make it a much more complete system than any other before that.
Affectionately,
Alok Da
Follow-up question:
Sri Aurobindo has talked about Sankhya(of Kapil Mahamuni) in his Essays on the Gita. Am I right, Alok Da?
Yes, but with reference to the Gita. He has also spoken about it in the Synthesis of Yoga, Letters on Yoga, volumes 1 and 2, and Karmayogin.
Affectionately,
Alok Da
