In the Sanatana Dharma (Eternal Truth), Samkhya provides the cosmological structure, Vedanta , the uncompromising and unalloyed Truth of indivisible Existence, Knowledge and Bliss, and Tantra and Yoga offer and define the method and the practice. All of the above, together, represent the consummate path and way.
In Samkhya , since atman (Purusa) is pure consciousness , which cannot be defined further, and Prakrti is responsible for the creation of the empirical world , Purusa is regarded as essentially inactive. But, while in Advaita , the multitude of souls (of course, the karmic chain of transmigration might hold together one and the same soul but they are supposed to be innumerable chains representing different souls) is only valid on the empirical, lower stage of reality.
Yoga, Vedanta and Tantra owe much of their basis and growth to the Samkhya philosophy which enumerates the twenty-four cosmic principles as a basis for the universal manifestation. This steady foundation assisted in the presentation of the life-giving, life-saving, life-transforming declarations of the Vedas. Due to this structure, Tantra gave birth to the many wonderful methods through which to realize the Truth contained in the Vedas and over time graced the system with twelve more powerful principles (tattvas) of a higher and purer order.