Six systems—There are six systems of philosophy associated with the Vedic scriptures. These together are known as the ṣaḍ-darśana. The ṣaḍ-darśana (six views) are: 1) Nyāya (logic), 2) Vaiśeṣika (atomic theory), 3) Sāṅkhya (analysis of matter and spirit), 4) Yoga (the discipline of self-realization), 5) Karma-mīmāṁsā (the science of fruitive work) and 6) Vedānta (the science of God realization). The ṣaḍ-darśana are termed āstika philosophies (from asti, or it is so), because they all acknowledge the Veda as authoritative, as opposed to the nāstika philosophies of the Cārvakas, Buddhists and Jains (nāsti, it is not so), who reject the Vedas. Beginning with Nyāya, each of the ṣaḍ-darśana in their turn presents a more developed and comprehensive explanation of the aspects of Vedic knowledge. Nyāya sets up the rules of philosophical debate and identifies the basic subjects under discussion: the physical world, the soul, God and liberation. Vaiśeṣika engages the method of Nyāya or logic in a deeper analysis of the predicament of material existence by showing that the visible material forms to which we are all so attached ultimately break down into invisible atoms. Sāṅkhya develops this analytical process further to help the soul become aloof to matter. Through Yoga, the soul awakens its innate spiritual vision to see itself beyond the body. Karma-mīmāṁsā directs the soul to the goals of Vedic ritualism. Vedānta ultimately focuses on the supreme spiritual goal taught in the Upaniṣads. As can be seen in Śrīmad-Bhāgavatam, the basis of these darśanas was an original, unified spiritual science (bhagavad-tattva-vijñāna) taught in very olden times by the twelve Mahājanas: Brahmā, Nārada, Śiva, Kumāras, Kapila, Manu, Prahlāda, Janaka, Bhīṣma, Bali, Śukadeva and Yamarāja. But due to the influence of māyā, scholars who followed the teachings of later sages like Gautama, Kaṇāda, Nirīśvara Kapila, Patañjali and Jaimini, became divided and contentious. The Vedic philosophy was misunderstood, and opposing schools came into being to serve sectarian ends. For instance, Karma-mīmāṁsā (which by 500 BC had become the foremost philosophy of the brāhmaṇa class) was misused by bloodthirsty priests to justify their mass slaughter of animals in Vedic sacrifices. But the unexpected rise of a novel non-Vedic religion challenged the power of Karma-mīmāṁsā. This new religion was Buddhism. By 250 BC, the influence of Karma-mīmāṁsā and other darśanas had weakened considerably. When King Aśoka instituted the Buddha's doctrine as the state philosophy of his empire, many brāhmaṇas abandoned Vedic scholarship to learn and teach nāstika concepts of ahiṁsā (nonviolence) and śūnyatā (voidism). Buddhism in its turn was eclipsed by the teachings of the Vedāntist Śaṅkarācārya, who revived the Vedic culture all over India in the seventh century after Christ. But Śaṅkarācārya's special formulation of Vedānta was itself influenced by Buddhism and is not truly representative of the original Vedānta-darśana. After Śaṅkarācārya, Vedānta was refined by the schools of great teachers (ācāryas) like Rāmānuja and Madhva. Having shed the baggage of Śaṅkarācārya's crypto-Buddhism, Vedānta philosophers brought Vedic studies back to their original form as seen in Śrīmad-Bhāgavatam. See Advaita, Analysis, Dvaita, Four Vaiṣṇava Sampradāyas and Siddhāntas, Māyāvāda philosophy, Veda, Vedānta.