there is what we may call an intelligence of the life-mind, dynamic, vital, nervous, more open, though still obscurely, to the psychic, capable of a first soul-formation, though only of an obscurer life-soul — not the psychic being, but a frontal formation of the vital Purusha.
Aurobindo introduces ‘life-soul’ as a precise technical term for a subliminal vital formation distinct from the full psychic being, occupying an intermediate ontological level between physical mind and true soul.
, The Life Divine, 1939thesis