Sankya is a system of indian philosophy, which is the closest one to the vedic system.
Sankya is a term coined from the word sankya – number. They accept 25 substances.
The system was first taught by Bhagawan Kapila maharishi. Though, we find a similar name in bhagavad purana, the teaching there is of advaita (monistic).
For them Purusha is the Self, which is not associated with anything.
Prakrti / pradhana is the cause of the creation. It consists of three gunas, Sattva, Rajas and Tamas. When the gunas loose their equilibrium, the creation starts.
The creation happens for the Experience and Realization of the Purusha.
Purusha, Prakriti, Mahat (intellect), Ahamkara (ego), 5 Tanmatra (the source of elements), 5 mahabootas (elements), 5 Jnana indriya (organ of knowledge), 5 Karma indriya (organ of action) and Manas (mind) are the 25 tattvas.
By seeing the true nature of the Prakriti the Purusha, who is ever free, understands his true nature and gets released from the bondage. This release is of the nature of the destruction of the three types of Dukka (sorrow), Adyatmika, Adibautika and Adidaivika.
Here Purusha is neither cause nor an efffect.Prakriti is merely a cause.Mahat, Ahamkara and 5 Tanmatras are both cause and effect.The rest are only an effect.
Sankya sutra by Bhagawan Kapila maharishi.
Sankya Karika by Sri Ishwara krishna is famous, in only 70 odd slokas, he summarises the whole of the teaching brilliantly.
Sankya Tattwa Kaumudi by Sri Vachaspati Mishra, is a famous commentory on the karika. Though, the karika clearly demarcates itself from condmning other schools, and sticks to only proving the sankya system. This commentory, goes to prove that the system of Sankya is the only correct philosophy. As is common with the other commentories of the author on the other school of philosophies.
The simplest and good commentory on this Karika is the bhashya by Sri Gaudapadacharya. It is not clear wheather, this is the same Gaudapada as the Paramaguru of Sri Sankaracharya and Mandukya Karikakara.
For more Detailed knowledge :
We have the book in Tamil. Books -> Sankya
For lectures on Sankya both in English and Tamil : Lectures -> Sankya
For Video Visit : http://www.youtube.com/user/Shastralayam#p/u