Sankhya’s view of existence essentially posits the Purusha, essentially the non-acting, non-moving witness consciousness, and the Prakriti, the active Nature. One key insight which has serious practical application in daily life is the interaction of the 3 modes of energy.
Sri Aurobindo describes them: “For Prakriti is constituted of three Gunas or essential modes of energy; Sattwa, the seed of intelligence, conserves the workings of energy; Rajas, the seed of force and action, creates the workings of energy; Tamas, the seed of inertia and non-intelligence, the denial of Sattwa and Rajas, dissolves what they create and conserve.”
According to the Sankhya view, all action in nature is due to the disequilibrium of these three gunas and their constant interaction. “But when the equilibrium is disturbed, then the three Gunas fall into a state of inequality in which they strive with and act upon each other and the whole inextricable business of ceaseless creation, conservation and dissolution begins, unrolling the phenomena of the cosmos.”
In order for this action to take place, the consent of the Purusha to reflect this action is required. “This reflection and this giving or withdrawal of consent seem to be the only powers of Purusha; he is the witness of Nature by virtue of reflection and the giver of the sanction….but not actively the Ishwara. Even his giving of consent is passive and his withdrawing of consent is only another passivity.”
Because the soul is inactive, it means “…Soul and Nature are the dual cause, a passive Consciousness and an active Energy.”
Sri Aurobindo, Essays on the Gita, First Series, Chapter 8, Sankhya and Yoga, pp. 65-66,
Sri Aurobindo Studies 