Ishvarakrishna composed the Samkhya Karika in the terse verse form, karika, meant to be memorized and expanded through a teacher's oral commentary rather than read as a self-contained exposition, a common format for early Indian philosophical texts. Most scholars place its composition around the fourth or fifth century CE, though the system it summarizes is considerably older. Its doctrine holds that reality consists of exactly two independent kinds of principle: purusha, pure consciousness, present as a distinct instance for every individual being rather than as a single shared consciousness, and prakriti, primordial undifferentiated matter, which alone is active and productive. Their proximity, on this account, sets prakriti evolving, unfolding through a fixed sequence into the twenty five tattvas, principles, that make up the entire manifest world, including mind, ego and the senses, all classed as products of prakriti rather than of consciousness itself. Liberation in this system comes not from any external salvation but from purusha correctly recognizing its own total separateness from prakriti and everything prakriti produces, ending its mistaken identification with a body and mind that were never truly its own.