Sankhya-Yoga a system of Hindu thought that posits two sorts of reality, immaterial (purusha) and material (prakrti). Prakrti, a physical stuff composed of what is lightweight and finegrained (sattva), what is heavy and coarse (tamas), and what is active (rajas), is in some sense the source of matter, force, space, and time. Sankhya physical theory explains the complex by reference to the properties of its components.
The physical universe everlastingly oscillates between states in which the three elements exist unmixed and states in which they mingle; when they mingle, they compose physical bodies some of which incarnate bits of purusha. When the basic elements mingle, transmigration occurs. Pursha is inherently passive, and mental properties belong only to the composite of prakrti and purusha, leading critics to ask what, when the physical elements are separated, individuates one mind from another. The answer is that one bit of purusha has one transmigratory history and another bit has another history. Critics (e.g., Nyaya-Vaishesika philosophers) were not satisfied with this answer, which allowed no intrinsic distinctions between bits of non-incarnate purusha. The dialectic of criticism led to Advaita Vedanta (for which all purusha distinctions are illusory) and other varieties of Vedanta (Dvaita and Visistadvaita) for which minds have inherent, not merely embodied, consciousness. Sankhya claims that there can be no emergent properties (properties not somehow a reshuffling of prior properties), so the effect must in some sense preexist in the cause.
See also HINDUIS. K.E.Y.