The Sánkhya system of Kapila is contained in many works, but notably in the Káriká, or Sánkhya-Káriká, by Iswara Krishna. This consists in eighty-two memorial verses, with a commentary.[62] The Vedanta is contained in the Sutras, the Upanishads, and especially the Brahma-Sutra attributed to Vyasa.[63] The Nyaya is to be found in the Sutras of Gotama and Canade.[64] These three systems of Hindoo philosophy, the Sánkhya, the Nyaya, and the Vedanta, reach far back into a misty twilight, which leaves it doubtful when they began or who were their real authors. In some points they agree, in others they are widely opposed. They all agree in having for their object deliverance from the evils of time, change, sorrow, into an eternal rest and peace. Their aim is, therefore, not merely speculative, but practical. All agree in considering existence to be an evil, understanding by existence a life in time and space. All are idealists, to whom the world of sense and time is a delusion and snare, and who regard the Idea as the only substance. All agree in accepting the fact of transmigration, the cessation of which brings final deliverance. All consider that the means of this deliverance is to be found in knowledge, in a perfect knowledge of reality as opposed to appearance. And all are held by Brahmans, who consider themselves orthodox, who honor the Vedas above all other books, pay complete respect to the Hinduism of the day, perform the daily ceremonies, and observe the usual caste rules.[65] The systems of philosophy supplement the religious worship, but are not intended to destroy it. The Vedantists hold that while in truth there is but one God, the various forms of worship in the Vedas, of Indra, Agni, the Maruts, etc., were all intended for those who could not rise to this sublime monotheism. Those who believe in the Sánkhya maintain that though it wholly omits God, and is called "the system without a God," it merely omits, but does not deny, the Divine existence.[66] Each of these philosophies has a speculative and a practical side. The speculative problem is, How did the universe come? The practical problem is, How shall man be delivered from evil? In answering the first question, the Vedanta, or Mimansa doctrine, proceeds from a single eternal and uncreated Principle; declaring that there is only ONE being in the universe, God or Brahm, and that all else is Maya, or illusion. The Sankhya accepts TWO eternal and uncreated substances, Soul and Nature. The Nyaya assumes THREE eternal and uncreated substances,--Atoms, Souls, and God. The solution of the second problem is the same in all three systems. It is by knowledge that the soul is emancipated from body or matter or nature. Worship is inadequate, though not to be despised. Action is injurious rather than beneficial, for it implies desire. Only knowledge can lead to entire rest and peace.