BhagavadGita

The six major schools of Indian philosophy, known as Astika schools, are: Nyaya, Vaisheshika, Samkhya, Yoga, Purva Mimamsa, and Uttara Mimamsa (Vedanta). These schools are considered orthodox because they accept the authority of the Vedas. 

Here's a brief overview of each school: 

• Nyaya:
  Focuses on logic and epistemology, aiming to understand the means of acquiring knowledge.

• Vaisheshika:
  Deals with atomic theory and the categorization of the world based on different attributes.

• Samkhya:
  Explores the nature of reality through the dualistic concepts of Purusha (consciousness) and Prakriti (matter).

• Yoga:
  Emphasizes the practice of yoga to achieve liberation and self-realization.

• Purva Mimamsa:
  Focuses on the proper interpretation and performance of Vedic rituals.

• Uttara Mimamsa (Vedanta):
  Interprets the Upanishads and Brahman, exploring the nature of ultimate reality and self.

उत्पत्तिं प्रलयं चैव भूतानामागतिं गतिम् |
वेत्तिं विद्यामविद्यां च स वाच्यो भगवानिति ||

He who understands the creation and dissolution, the appearance and disappearance of beings, the wisdom and ignorance, should be called Bhagavān. — Vishnu Purana, VI.5.78

The Gītā is an attempt at bringing together all the salient factors in all schools of thought to a happy synthesis. In the Gītā we are shown the merits and demerits of all the schools. It teaches us how to make use of them all without prejudice, so that ultimately we may reach the acme of Perfection – as described in the immortal doctrine of Vedānta.