The distinction between Purusha and Prakriti is a practical aid in the development of the yogic process as it provides the seeker with a standpoint from which to view, for a distance of psychological separation, the actions of nature within his being, and thereby assist in the process of releasing him from the bondage of Nature and the ego-nexus. Western psychology recognizes that one cannot see the frame within which one operates–the standpoint of the Purusha creates a new standpoint from which to view what otherwise is the field of action for the individual. At the same time, the distinction of Purusha-Prakriti does not change the fact that the individual is not the initiator of action nor the actor. It remains Nature that acts through the individual nexus.
Sri Aurobindo reminds us that “Again and always it is the transcendent and universal Shakti who is the sole doer. But behind her is the one Supreme who manifests through her as the dual power, Purusha-Prakriti, Ishwara-Shakti. The Supreme becomes dynamic as the Shakti and is by her the sole originator and Master of works in the universe.”
Sri Aurobindo also clarifies: “Ishwara-Shakti is not quite the same as Purusha-Prakriti; for Purusha and Prakriti are separate powers but Ishwara and Shakti contain each other. Ishwara is Purusha who contains Prakriti and rules by the power of the Shakti within him. Shakti is Prakriti ensouled by Purusha and acts by the will of the Ishwara which is her own will and whose presence in her movement she carries always with her.”
“Ishwara-Shakti stands behind the relation of Purusha-Prakriti and its ignorant action and turns it to an evolutionary purpose. The Ishwara-Shakti realisation can bring participation in a higher dynamism and a divine working and a total unity and harmony of the being in a spiritual nature.”
Sri Aurobindo, The Synthesis of Yoga, Part One: The Yoga of Divine Works, Chapter 8, The Supreme Will, pp.204-205